<table><caption>**Table 33.** Calculated photodissociation & photoionization rates of HF.</caption><thead><tr><th>Radiation field</th><th>Photodissociation (s<sup>-1</sup>) – this work</th><th>Photoionization (s<sup>-1</sup>) – this work</th></tr></thead><tbody><tr><td>ISRF</td><td>1.38E-10</td><td>0</td></tr><tr><td>Mathis '83</td><td>9.85E-11</td><td>0</td></tr><tr><td>4000 K</td><td>5.31E-13</td><td>0</td></tr><tr><td>10 000 K</td><td>2.88E-11</td><td>0</td></tr><tr><td>20 000 K</td><td>1.17E-10</td><td>0</td></tr><tr><td>Lyman-α</td><td>4.93E-10</td><td>0</td></tr><tr><td>Solar</td><td>2.18E-11</td><td>2.45E-13</td></tr><tr><td>TW-Hya</td><td>3.19E-10</td><td>2.13E-12</td></tr><tr><td>Cosmic-ray UV</td><td>1.93E-13</td><td>2.04E-15</td></tr></tbody></table>

<table><caption>**Table 34.** Summary of all updates and new species added to the database.</caption><thead><tr><th>Species</th><th>Thresh. dissoc. prod.</th><th>Dissoc. thresh. (nm)</th><th>Ioniz./photodet.</th><th>Uncert. dissoc.</th><th>Uncert. ioniz./photodet.</th></tr></thead><tbody><tr><td>H<sub>3</sub><sup>+</sup></td><td>H<sup>+</sup> + H<sub>2</sub></td><td>282</td><td>–</td><td>A</td><td>–</td></tr><tr><td>CH</td><td>C + H</td><td>358</td><td>117</td><td>C</td><td>A</td></tr><tr><td>C<sub>2</sub></td><td>C + C</td><td>193</td><td>102</td><td>B</td><td>B</td></tr><tr><td>C<sub>2</sub>H</td><td>C<sub>2</sub> + H</td><td>253</td><td>107</td><td>B</td><td>B</td></tr><tr><td>C<sub>2</sub>H<sup>-</sup></td><td>–</td><td>–</td><td>412</td><td>–</td><td>A+</td></tr><tr><td>C<sub>2</sub>H<sub>3</sub></td><td>H<sub>2</sub>CC + H</td><td>1240</td><td>147</td><td>C</td><td>C</td></tr><tr><td>C<sub>2</sub>H<sub>5</sub></td><td>C<sub>2</sub>H<sub>4</sub> + H</td><td>260</td><td>153</td><td>C</td><td>A+</td></tr><tr><td>I-C<sub>3</sub>H</td><td>C<sub>3</sub> + H</td><td>379</td><td>136</td><td>B</td><td>B</td></tr><tr><td>c-C<sub>3</sub>H</td><td>C<sub>3</sub> + H</td><td>289</td><td>126</td><td>B</td><td>B</td></tr><tr><td>HC<sub>3</sub>H</td><td>I-C<sub>3</sub>H + H</td><td>400</td><td>139</td><td>B</td><td>B</td></tr><tr><td>c-C<sub>3</sub>H<sub>2</sub></td><td>c-C<sub>3</sub>H + H</td><td>284</td><td>136</td><td>B</td><td>B</td></tr><tr><td>C<sub>3</sub>H<sub>3</sub></td><td>C<sub>3</sub>H<sub>2</sub> + H/C<sub>3</sub>H + H<sub>2</sub></td><td>300</td><td>143</td><td>C</td><td>A+</td></tr><tr><td>C<sub>4</sub>H<sup>-</sup></td><td>–</td><td>–</td><td>348</td><td>–</td><td>A+</td></tr><tr><td>C<sub>6</sub>H<sup>-</sup></td><td>–</td><td>–</td><td>327</td><td>–</td><td>A+</td></tr><tr><td>OH</td><td>O + H</td><td>279</td><td>95</td><td>A+</td><td>A+</td></tr><tr><td>HO<sub>2</sub></td><td>H + O<sub>2</sub></td><td>476</td><td>109</td><td>C</td><td>A+</td></tr><tr><td>HCO</td><td>H + CO</td><td>2037</td><td>152</td><td>C</td><td>A+</td></tr><tr><td>HCOOH</td><td>H + HCOO</td><td>333</td><td>110</td><td>A+</td><td>A+</td></tr><tr><td>NH<sub>2</sub></td><td>NH + H</td><td>314</td><td>111</td><td>C</td><td>A+</td></tr><tr><td>HNC</td><td>H + NC</td><td>165</td><td>103</td><td>B</td><td>B</td></tr><tr><td>HNCO</td><td>NH + CO</td><td>333</td><td>108</td><td>A</td><td>B</td></tr><tr><td>CH<sub>3</sub>CHO</td><td>HCO + CH<sub>3</sub></td><td>342</td><td>121</td><td>A</td><td>A</td></tr><tr><td>CH<sub>3</sub>OCH<sub>3</sub></td><td>CH<sub>3</sub>O + CH<sub>3</sub></td><td>196</td><td>127</td><td>A+</td><td>A+</td></tr><tr><td>CH<sub>3</sub>OCHO</td><td>CH<sub>3</sub>O + CHO</td><td>248</td><td>113</td><td>A+</td><td>A+</td></tr><tr><td>SH</td><td>S + H</td><td>345</td><td>119</td><td>B</td><td>A+</td></tr><tr><td>CS</td><td>C + S</td><td>168</td><td>110</td><td>A+</td><td>A</td></tr><tr><td>H<sub>2</sub>CS</td><td>H<sub>2</sub> + CS</td><td>313</td><td>135</td><td>A</td><td>B</td></tr><tr><td>S<sub>2</sub></td><td>S + S</td><td>280.6</td><td>133</td><td>A+</td><td>B</td></tr><tr><td>SiH</td><td>Si + H</td><td>417</td><td>156</td><td>B</td><td>B</td></tr><tr><td>HF</td><td>H + F</td><td>140</td><td>78</td><td>A+</td><td>B</td></tr></tbody></table>

however, or photodissociation products in this wavelength range (Deyerl et al. 1999; Nguyen et al. 2001a,b; Zheng et al. 2009). The photodissociation cross section included here is, therefore, a scaled combination of the two transitions from the Eisfeld spectra which agree with experiments, and are absolutely scaled to the cross section measured previously (Fahr et al. 1997).

### 3.11. C<sub>4</sub>H<sup>-</sup> and C<sub>6</sub>H<sup>-</sup>

As with C<sub>2</sub>H<sup>-</sup>, the absolute photodetachment cross sections of both C<sub>4</sub>H<sup>-</sup> and C<sub>6</sub>H<sup>-</sup> have been measured with 22-pole ion

trap technology at several photon energies which allows the construction of the cross sections (Best et al. 2011). Their cross sections are included in this database now for the first time.

### 3.12. OH (hydroxyl)

Previously, the photodissociation cross section of OH is based on the theoretical work by van Dishoeck & Dalgarno (van Dishoeck et al. 1984; van Dishoeck & Dalgarno 1984a,b). More recently, the VUV photoabsorption spectra of the A<sup>2</sup>Σ<sup>+</sup> (ν' = 0) and D<sup>2</sup>Σ<sup>-</sup> (ν' = 0, 1) bands of OH (and OD) were
recorded (Heays et al. 2018) using the Fourier transform absorp-
tion cell at the DESIRS beamline at SOLEIL (de Oliveira et al.
2011, 2016). The high resolution spectra allowed the relative
oscillator strengths of these bands to be determined with greater
accuracy than before, and these are used to rescale the cross sec-
tion previously included. This results in an increase by 12.5% of
the photodissociation cross section of OH and improves the
accuracy grade to A+.

More recently, however, the absolute photoionization cross
section of OH has been measured by two groups (Dodson et al.
2018; Harper et al. 2019, 2020b) using i²PEPICO spectroscopy
but employing different techniques in terms of preparing the
OH radicals. Both cross sections are recorded in high resolution
revealing a wealth of autoionizing resonances. The ionization
energy is measured to be IE = 13.06198 eV = 94.9199 nm and this
is the first time the OH photoionization cross section is included
in the database.

3.13. HO₂ (superoxide)

The photodissociation cross section of superoxide has been
included in previous editions of the database. It is obtained from
a combination of theory (Langhoff & Jaffe 1979) and experi-
ments (McAdam et al. 1987). The absolute photoionization cross
section has been measured by Dodson et al. (2015) and is now
included in the database for the first time.

3.14. HCO (formyl)

As before, the photodissociation cross section of the formyl rad-
ical is based on the theoretical work of Bruna et al. (1976).
More recently, the absolute photoionization cross section of the
formyl radical was recently measured by Savee et al. (2021) up
to 11.5 eV (108 nm). The ionization energy is measured as IE =
8.15022 eV (152.124 nm) and we extend the photoionization
cross section toward 91.2 nm.

3.15. HCOOH (formic acid)

The photodissociation dynamics of formic acid have been stud-
ied at several wavelengths (Jolly et al. 1987; Suto et al. 1988a;
Singleton et al. 1989, 1990; Shin et al. 1998), but one of the first
absorption (dissociation) cross sections of formic acid was mea-
sured from 195 to 250 nm by Singleton et al. (1987). However,
it was found that the first dissociation threshold of HCOOH is
somewhat lower, or 333 nm which corresponds to the cleavage
of the HCOO-H bond whereas the dissociation threshold for
the H-COOH bond is measured to be 255 nm (Langford et al.
1997). Above 200 nm we thus include the cross section mea-
sured by Singleton et al. and a 5 × 10⁻²⁰ cm² baseline toward the
photodissociation threshold of 333 nm.

Below 200 nm, the absorption cross section between 105 and
155 nm has been recorded (Tabayashi et al. 1999) and oscillator
strengths have been calculated for several electronically excited
states (Osted et al. 2005). Later absorption cross section mea-
surements in higher resolution were performed by Leach et al.
(2002) and Schwell et al. (2006). The photoionization cross sec-
tion of formic acid was measured from threshold (11.3 eV =
110 nm) up to 12.4 eV (= 100 nm) (Cool et al. 2005) and
by combining all these previous measurements of absorption
cross sections, photoionization yields, Fujimoto et al. (2020)
could derive the photoemission decay cross section above the
photoionization threshold which allowed them to appropriately
derive and scale the absolute photoionization cross section with

better than 10% accuracy. Cross sections for HCOOH are also
available toward X-ray regimes (Boechat-Roberty et al. 2005;
Tenorio et al. 2019).

3.16. NH₂ (amidogen)

The photodissociation cross section of NH₂ was con-
structed from previous calculations (Saxon et al. 1983;
Koch 1997; Yamaguchi et al. 1999) and is here unchanged. The
photoionization cross section that was previously included was
a scaling of the photoionization efficiency curve that was mea-
sured by Gibson et al. (1985), but this cross section has recently
been determined in absolute terms with an error around 5%
(Harper et al. 2021). The recent measurement by Harper et al.
gives a cross section whose intensity is approximately a factor of
2 smaller than the previously scaled photoion yield. Their cross
section is herewith added to the database.

3.17. HNC (hydrogen isocyanide)

HNC is a very tricky molecule to work in a labora-
tory setting. Hence, very few experimental studies exist
which have investigated its physical and chemical properties.
Although theoretically challenging as well, its photoabsorp-
tion/dissociation cross sections have been calculated along with
the HCN using ab initio methods up to 13.6 eV (Aguado et al.
2017). The cross section is very structured with many discrete
features and is added to the database now for the first time.

The photoionization cross section has been constructed from
the following experiments. By using methanimine (CH₂NH) as a
precursor and F radicals for H-abstraction, both HNC and HCN
were created in the flow-tube contraption described previously
(Gans et al. 2019). As the ionization energy of HNC is approx-
imately 1.5 eV lower than HCN, the ionization of HNC could
be comfortably studied below the ionization threshold of HCN.
The ground state TPES was well reproduced by theory which
was used to simulate the TPES of the first excited cationic state.
By integrating the TPES in a manner similar to l-C₃H, c-C₃H,
l-C₃H₂, and c-C₃H₂ (see above) the total ion yield curve of
HNC could be constructed and scaled to give a photoionization
cross section.

3.18. HNCO (isocyanic acid)

HNCO emission from G+0.693-0.03 has been used to infer two
colliding gaseous components, that is, a collision of two molec-
ular clouds which gives rise to the rich and peculiar chemistry
therein (Zeng et al. 2020).

An ultraviolet absorption spectrum of HNCO was recorded
in the 1960s (Dixon & Kirby 1968) covering 200–260 nm but a
more extended UV absorption cross section measurement was
obtained a few years later (Okabe 1970). This cross section
is used here with the previous UV absorption measurement
scaled to extend the cross section down to 260 nm. It has been
observed, however, that the first photodissociation channel opens
at 333 nm to give CO + NH, but no cross sections exist in
this region. Hence, we add a baseline of 5 × 10⁻²⁰ cm² down
to the dissociation limit in a similar manner as HCOOH (see
above). The photodissociation dynamics of the first three lowest-
energy photodissociation channels have been investigated with
VMI (Zhang et al. 2014a, 2018a,b). In brief, these three dissocia-
tion channels are the following: (i) NH(X)+CO(X) (332.67 nm),
(ii) H²S)+NCO(X) (260.62 nm), and (iii) NH(a¹Δ)+CO(X)
(236.55 nm).
recorded (Heays et al. 2018) using the Fourier transform absorp-
tion cell at the DESIRS beamline at SOLEIL (de Oliveira et al.
2011, 2016). The high resolution spectra allowed the relative
oscillator strengths of these bands to be determined with greater
accuracy than before, and these are used to rescale the cross sec-
tion previously included. This results in an increase by 12.5% of
the photodissociation cross section of OH and improves the
accuracy grade to A+.

More recently, however, the absolute photoionization cross
section of OH has been measured by two groups (Dodson et al.
2018; Harper et al. 2019, 2020b) using i²PEPICO spectroscopy
but employing different techniques in terms of preparing the
OH radicals. Both cross sections are recorded in high resolution
revealing a wealth of autoionizing resonances. The ionization
energy is measured to be IE = 13.06198 eV = 94.9199 nm and this
is the first time the OH photoionization cross section is included
in the database.

3.13. HO₂ (superoxide)

The photodissociation cross section of superoxide has been
included in previous editions of the database. It is obtained from
a combination of theory (Langhoff & Jaffe 1979) and experi-
ments (McAdam et al. 1987). The absolute photoionization cross
section has been measured by Dodson et al. (2015) and is now
included in the database for the first time.

3.14. HCO (formyl)

As before, the photodissociation cross section of the formyl rad-
ical is based on the theoretical work of Bruna et al. (1976).
More recently, the absolute photoionization cross section of the
formyl radical was recently measured by Savee et al. (2021) up
to 11.5 eV (108 nm). The ionization energy is measured as IE =
8.15022 eV (152.124 nm) and we extend the photoionization
cross section toward 91.2 nm.

3.15. HCOOH (formic acid)

The photodissociation dynamics of formic acid have been stud-
ied at several wavelengths (Jolly et al. 1987; Suto et al. 1988a;
Singleton et al. 1989, 1990; Shin et al. 1998), but one of the first
absorption (dissociation) cross sections of formic acid was mea-
sured from 195 to 250 nm by Singleton et al. (1987). However,
it was found that the first dissociation threshold of HCOOH is
somewhat lower, or 333 nm which corresponds to the cleavage
of the HCOO-H bond whereas the dissociation threshold for
the H-COOH bond is measured to be 255 nm (Langford et al.
1997). Above 200 nm we thus include the cross section mea-
sured by Singleton et al. and a 5 × 10⁻²⁰ cm² baseline toward the
photodissociation threshold of 333 nm.

Below 200 nm, the absorption cross section between 105 and
155 nm has been recorded (Tabayashi et al. 1999) and oscillator
strengths have been calculated for several electronically excited
states (Osted et al. 2005). Later absorption cross section mea-
surements in higher resolution were performed by Leach et al.
(2002) and Schwell et al. (2006). The photoionization cross sec-
tion of formic acid was measured from threshold (11.3 eV =
110 nm) up to 12.4 eV (= 100 nm) (Cool et al. 2005) and
by combining all these previous measurements of absorption
cross sections, photoionization yields, Fujimoto et al. (2020)
could derive the photoemission decay cross section above the
photoionization threshold which allowed them to appropriately
derive and scale the absolute photoionization cross section with

better than 10% accuracy. Cross sections for HCOOH are also
available toward X-ray regimes (Boechat-Roberty et al. 2005;
Tenorio et al. 2019).

3.16. NH₂ (amidogen)

The photodissociation cross section of NH₂ was con-
structed from previous calculations (Saxon et al. 1983;
Koch 1997; Yamaguchi et al. 1999) and is here unchanged. The
photoionization cross section that was previously included was
a scaling of the photoionization efficiency curve that was mea-
sured by Gibson et al. (1985), but this cross section has recently
been determined in absolute terms with an error around 5%
(Harper et al. 2021). The recent measurement by Harper et al.
gives a cross section whose intensity is approximately a factor of
2 smaller than the previously scaled photoion yield. Their cross
section is herewith added to the database.

3.17. HNC (hydrogen isocyanide)

HNC is a very tricky molecule to work in a labora-
tory setting. Hence, very few experimental studies exist
which have investigated its physical and chemical properties.
Although theoretically challenging as well, its photoabsorp-
tion/dissociation cross sections have been calculated along with
the HCN using ab initio methods up to 13.6 eV (Aguado et al.
2017). The cross section is very structured with many discrete
features and is added to the database now for the first time.

The photoionization cross section has been constructed from
the following experiments. By using methanimine (CH₂NH) as a
precursor and F radicals for H-abstraction, both HNC and HCN
were created in the flow-tube contraption described previously
(Gans et al. 2019). As the ionization energy of HNC is approx-
imately 1.5 eV lower than HCN, the ionization of HNC could
be comfortably studied below the ionization threshold of HCN.
The ground state TPES was well reproduced by theory which
was used to simulate the TPES of the first excited cationic state.
By integrating the TPES in a manner similar to l-C₃H, c-C₃H,
l-C₃H₂, and c-C₃H₂ (see above) the total ion yield curve of
HNC could be constructed and scaled to give a photoionization
cross section.

3.18. HNCO (isocyanic acid)

HNCO emission from G+0.693-0.03 has been used to infer two
colliding gaseous components, that is, a collision of two molec-
ular clouds which gives rise to the rich and peculiar chemistry
therein (Zeng et al. 2020).

An ultraviolet absorption spectrum of HNCO was recorded
in the 1960s (Dixon & Kirby 1968) covering 200–260 nm but a
more extended UV absorption cross section measurement was
obtained a few years later (Okabe 1970). This cross section
is used here with the previous UV absorption measurement
scaled to extend the cross section down to 260 nm. It has been
observed, however, that the first photodissociation channel opens
at 333 nm to give CO + NH, but no cross sections exist in
this region. Hence, we add a baseline of 5 × 10⁻²⁰ cm² down
to the dissociation limit in a similar manner as HCOOH (see
above). The photodissociation dynamics of the first three lowest-
energy photodissociation channels have been investigated with
VMI (Zhang et al. 2014a, 2018a,b). In brief, these three dissocia-
tion channels are the following: (i) NH(X)+CO(X) (332.67 nm),
(ii) H²S)+NCO(X) (260.62 nm), and (iii) NH(a¹Δ)+CO(X)
(236.55 nm).
The photoelectron spectrum of HNCO was initially recorded with low resolution by Eland (1970) and was more recently measured in higher resolution where the TPES of the ground state and first excited states of the cation was obtained (Holzmeier et al. 2015). To construct a photoionization cross section we integrate the lower-resolution PES which was recorded up to 19 eV (Eland 1970). This integrated PES was then scaled such that the ratio between the maximum intensity of the photoionization cross section and the photodissociation cross section was similar as those of HNC and HCN.

### 3.19. CH₃CHO (acetaldehyde)

The VUV photoabsorption cross section of acetaldehyde was previously measured by Martinez et al. (1992) and Limão-Vieira et al. (2003) up to 11 eV (113 nm). Some work pertaining to the nature of the photodissociation dynamics have also shown the first dissociation pathway leading to cleavage of the C-C bond to form CH₃ and CHO (Heazlewood et al. 2009). The wavelength-dependent VUV photodynamics of acetaldehyde, however, are rather complex and between 248 nm and 330 nm there are multiple fragmentation pathways which can lead to a variety of photoproducts such as H, H₂, CO, HCO, CH₄, and H₂CCO (Fu et al. 2012; Hung et al. 2014; Lee et al. 2014; Morajkar et al. 2014; Zhang et al. 2014b; Li et al. 2015; Han et al. 2017; Toulson et al. 2017; Shaw et al. 2018; Harrison et al. 2019; Yang et al. 2020, 2021).

Concerning the VUV photoionization of CH₃CHO, one of the first photoionization works was performed in the 1950s (Hurzeler et al. 1958). Its photoelectron spectrum and photoionization efficiency up to 20 eV was recorded by Yencha et al. (2013). Here we have taken their photoionization efficiency and scaled it in accordance to the calculations of the cross sections of high-lying Rydberg states (Vega et al. 2010). There it is assumed that the cross section drops shortly after the ionization onset.

### 3.20. CH₃OCH₃ (dimethyl ether)

The photoabsorption, photodissociation and photoionization cross sections of dimethyl ether (DME) have been studied in detail as DME is an important product species in combustion studies (Hatano 1999a). The cross sections between 50 and 95 nm were studied by Kameta et al. (1992) and from threshold up to 200 eV by Feng et al. (2000, 2001). Dissociative ionization of dimethyl ether is found to yield mostly H above 11.2 eV, and CH₃ in a minor yield up to 12.5 eV (Schwell et al. 2013).

The photodissociation products of DME, however, are not well constrained. Whilst some studies have found evidence of fluorescence from the methoxy (CH₃O) radical indicating a C–O bond cleavage to be the primary dissociation path (Suto et al. 1988b), it has also been found that through H-roaming, photodissociation of DME can also yield formaldehyde (HCHO) and methane (CH₄) (Tranter et al. 2013).

### 3.21. CH₃OCHO (methyl formate)

Methyl formate has been detected in young low-mass protostars (Bergner et al. 2017) and also with the FAUST survey of a three protostar system (Codella et al. 2022). It is included here in the database for the first time.

The VUV absorption spectrum of methyl formate has been recorded from 4 eV up to 11 eV by Nunes et al. (2010) who also recorded its photoelectron spectrum extending from 10.4 eV up to 17 eV. The photodissociation threshold is found to be 248 nm.

Here, we use their photoabsorption cross section as a basis for the photodissociation cross section. The dominant dissociation channel has been found to be the α-C–O bond fission through the S₁ electronically excited state leading to the formation of the methoxy (CH₃O) and formyl (HCO) radicals (Cui et al. 2010). The absolute photoionization cross section of methyl formate was measured from threshold up to 11.7 eV (Wang et al. 2010) which corresponds to the peak of the ground state photoelectron band (Nunes et al. 2010). To construct the photoionization cross section we sum over the measured photoelectron spectrum and use the absolute photoionization cross section by Wang et al. (2010) to provide scaling for the total cross section.

### 3.22. SH (mercapto)

The photodissociation cross section of SH has been included in the database previously and was obtained by combining the results of previous experimental and theoretical works (Johns & Ramsay 1961; Friedl et al. 1983; Bruna & Hirsch 1987; Lee et al. 2001; Lee & Sun 2001; Resende & Ornellas 2001). This cross section is here unchanged.

The absolute photoionization cross section of SH has been measured by recently (Hrodmarsson et al. 2019a). The error of the cross section is around 10%. Previously, the photoionization cross section of SH included in the database was arbitrarily simulated and was over an order of magnitude smaller than the recent measurements which also display a wealth of autoionizing resonances as well. The ionization energy is measured as 118.96 nm (Hrodmarsson et al. 2019a).

### 3.23. CS (carbon monosulfide)

CS has recently been observed to be quite abundant in hot cores (Barr et al. 2018). The photodissociation cross section of CS has been included in the database previously and was obtained by combining the results of previous experimental and theoretical works (Bruna et al. 1975; Stark et al. 1987). More recently, high level ab initio calculations have been employed to calculate the photodissociation cross section up to 90 nm. This is here included for the first time in the database (Xu et al. 2019).

The photoionization efficiency curve of CS has been measured around the ionization threshold (109.55 nm) (Norwood et al. 1991). The photoionization efficiency has also been measured between 60 and 85 nm (Coppens & Drowart 1995). The photoionization of CS using constant ionic state spectroscopy was also investigated up to 62 nm which revealed a very structured vibrational band on the cationic ground state (Dyke et al. 1998). They found that the ground state of the ion makes the most dominant contribution to the total ion yield and the signals from excited states of the cation made more negligible contributions. Hence, we assume an approximately constant ionic contribution from 100 nm to 80 nm. To scale these measurements of the photoionization efficiency we make use of calculations which consider both initial state configuration interaction (ISCI) and final ionic state configuration interactions (FISCI; Ponzi et al. 2014). These reveal that the maximum of the photoionization cross section of the autoionizing resonance toward the ionic ground state is around 20 Mb which allows us to scale the ionization cross section.

### 3.24. H₂CS (thioformaldehyde)

An ultraviolet absorption cross section of thioformaldehyde was initially measured at wavelengths longer than 220 nm
The photoelectron spectrum of HNCO was initially recorded with low resolution by Eland (1970) and was more recently measured in higher resolution where the TPES of the ground state and first excited states of the cation was obtained (Holzmeier et al. 2015). To construct a photoionization cross section we integrate the lower-resolution PES which was recorded up to 19 eV (Eland 1970). This integrated PES was then scaled such that the ratio between the maximum intensity of the photoionization cross section and the photodissociation cross section was similar as those of HNC and HCN.

### 3.19. CH₃CHO (acetaldehyde)

The VUV photoabsorption cross section of acetaldehyde was previously measured by Martinez et al. (1992) and Limão-Vieira et al. (2003) up to 11 eV (113 nm). Some work pertaining to the nature of the photodissociation dynamics have also shown the first dissociation pathway leading to cleavage of the C-C bond to form CH₃ and CHO (Heazlewood et al. 2009). The wavelength-dependent VUV photodynamics of acetaldehyde, however, are rather complex and between 248 nm and 330 nm there are multiple fragmentation pathways which can lead to a variety of photoproducts such as H, H₂, CO, HCO, CH₄, and H₂CCO (Fu et al. 2012; Hung et al. 2014; Lee et al. 2014; Morajkar et al. 2014; Zhang et al. 2014b; Li et al. 2015; Han et al. 2017; Toulson et al. 2017; Shaw et al. 2018; Harrison et al. 2019; Yang et al. 2020, 2021).

Concerning the VUV photoionization of CH₃CHO, one of the first photoionization works was performed in the 1950s (Hurzeler et al. 1958). Its photoelectron spectrum and photoionization efficiency up to 20 eV was recorded by Yencha et al. (2013). Here we have taken their photoionization efficiency and scaled it in accordance to the calculations of the cross sections of high-lying Rydberg states (Vega et al. 2010). There it is assumed that the cross section drops shortly after the ionization onset.

### 3.20. CH₃OCH₃ (dimethyl ether)

The photoabsorption, photodissociation and photoionization cross sections of dimethyl ether (DME) have been studied in detail as DME is an important product species in combustion studies (Hatano 1999a). The cross sections between 50 and 95 nm were studied by Kameta et al. (1992) and from threshold up to 200 eV by Feng et al. (2000, 2001). Dissociative ionization of dimethyl ether is found to yield mostly H above 11.2 eV, and CH₃ in a minor yield up to 12.5 eV (Schwell et al. 2013).

The photodissociation products of DME, however, are not well constrained. Whilst some studies have found evidence of fluorescence from the methoxy (CH₃O) radical indicating a C–O bond cleavage to be the primary dissociation path (Suto et al. 1988b), it has also been found that through H-roaming, photodissociation of DME can also yield formaldehyde (HCHO) and methane (CH₄) (Tranter et al. 2013).

### 3.21. CH₃OCHO (methyl formate)

Methyl formate has been detected in young low-mass protostars (Bergner et al. 2017) and also with the FAUST survey of a three protostar system (Codella et al. 2022). It is included here in the database for the first time.

The VUV absorption spectrum of methyl formate has been recorded from 4 eV up to 11 eV by Nunes et al. (2010) who also recorded its photoelectron spectrum extending from 10.4 eV up to 17 eV. The photodissociation threshold is found to be 248 nm.

Here, we use their photoabsorption cross section as a basis for the photodissociation cross section. The dominant dissociation channel has been found to be the α-C–O bond fission through the S₁ electronically excited state leading to the formation of the methoxy (CH₃O) and formyl (HCO) radicals (Cui et al. 2010). The absolute photoionization cross section of methyl formate was measured from threshold up to 11.7 eV (Wang et al. 2010) which corresponds to the peak of the ground state photoelectron band (Nunes et al. 2010). To construct the photoionization cross section we sum over the measured photoelectron spectrum and use the absolute photoionization cross section by Wang et al. (2010) to provide scaling for the total cross section.

### 3.22. SH (mercapto)

The photodissociation cross section of SH has been included in the database previously and was obtained by combining the results of previous experimental and theoretical works (Johns & Ramsay 1961; Friedl et al. 1983; Bruna & Hirsch 1987; Lee et al. 2001; Lee & Sun 2001; Resende & Ornellas 2001). This cross section is here unchanged.

The absolute photoionization cross section of SH has been measured by recently (Hrodmarsson et al. 2019a). The error of the cross section is around 10%. Previously, the photoionization cross section of SH included in the database was arbitrarily simulated and was over an order of magnitude smaller than the recent measurements which also display a wealth of autoionizing resonances as well. The ionization energy is measured as 118.96 nm (Hrodmarsson et al. 2019a).

### 3.23. CS (carbon monosulfide)

CS has recently been observed to be quite abundant in hot cores (Barr et al. 2018). The photodissociation cross section of CS has been included in the database previously and was obtained by combining the results of previous experimental and theoretical works (Bruna et al. 1975; Stark et al. 1987). More recently, high level ab initio calculations have been employed to calculate the photodissociation cross section up to 90 nm. This is here included for the first time in the database (Xu et al. 2019).

The photoionization efficiency curve of CS has been measured around the ionization threshold (109.55 nm) (Norwood et al. 1991). The photoionization efficiency has also been measured between 60 and 85 nm (Coppens & Drowart 1995). The photoionization of CS using constant ionic state spectroscopy was also investigated up to 62 nm which revealed a very structured vibrational band on the cationic ground state (Dyke et al. 1998). They found that the ground state of the ion makes the most dominant contribution to the total ion yield and the signals from excited states of the cation made more negligible contributions. Hence, we assume an approximately constant ionic contribution from 100 nm to 80 nm. To scale these measurements of the photoionization efficiency we make use of calculations which consider both initial state configuration interaction (ISCI) and final ionic state configuration interactions (FISCI; Ponzi et al. 2014). These reveal that the maximum of the photoionization cross section of the autoionizing resonance toward the ionic ground state is around 20 Mb which allows us to scale the ionization cross section.

### 3.24. H₂CS (thioformaldehyde)

An ultraviolet absorption cross section of thioformaldehyde was initially measured at wavelengths longer than 220 nm
(Drury & Moule 1982) but a more extensive absorption spectrum utilizing synchrotron radiation with higher resolution was recorded up to 130 nm (Chiang & Lin 2005). The latter measurements included ab initio calculations which gave oscillator strengths which helped scale the maxima of the absorption spectrum to the previously measured absolute cross sections. It is worth mentioning the theoretical efforts the ab initio calculations were based on which include many of the electronically excited states of H₂CS (Hachey & Grein 1995a,b).

A photoelectron spectrum of H₂CS was obtained via pyrolysis of CH₃SSCH₃ recorded by Kroto & Suffolk (1972). Although H₂S and CS₂ were also formed and visible in the PES, they can easily be subtracted such that the photoionization efficiency could be obtained by integrating the low-resolution PES and thus excluding the contributions from CS₂ and H₂S. The maximum was then scaled such that the scale of the cross section was similar to other sulfur containing molecules whose cross section has been measured in absolute terms, akin to what has been done with other carbon-based species.

The photodissociation of H₂CS has been subject to several experimental and theoretical studies and as a matter of fact, H₂CS has a benchmark status in theoretical studies because of the complex intersystem crossing dynamics involved in the excited states that partake in the photodissociation process (Zhang et al. 2021).

### 3.25. S₂ (disulfur, sulfur dimer)

The previous photodissociation cross section was made from a combination of experimental and theoretical works (Smith & Liszt 1971; Pradhan & Partridge 1996; Wheeler et al. 1998; Frederix et al. 2009). Recently, the absolute photoabsorption cross sections of the predissociative B–X system of S₂ has been measured in absolute terms by Stark et al. (2018) at two temperatures using the Fourier transform absorption cell at the DESIRS beamline at SOLEIL (de Oliveira et al. 2011, 2016). These measurements were accompanied by a comprehensive coupled-channel model describing the predissociative nature of the B–X system (Lewis et al. 2018). S₂ vapor was produced via an H₂S precursor gas in a radio frequency discharge for measurements at 370 K, or from solid elemental sulfur for spectra recorded at 823 K. These measurements have more recently been replicated computationally by Gomez et al. (in prep.). They calculated the absorption cross sections well below the dissociation threshold which has been measured as 280.6 nm by Frederix et al. (2009). Included in the database is the computational cross section which replicates the measurements at 370 K. The photoabsorption cross section corresponding to absorption by the B–X system below the dissociation threshold is included in the photoabsorption cross section available in the database online. It should be noted that the differences in the photodissociation rates from the measurements at the two temperatures (using the radiation fields in this work) were negligible.

The photoionization cross section of S₂ was previously made by scaling the photoionization efficiency curve measured by Liao & Ng (1986). Recently, this curve has been measured with higher resolution which has allowed assignments of multiple autoionizing resonances present in the total ion yield (Hrodmarsson et al. 2021). The total ion yield of S₂ was recorded in the same experiment which measured the absolute photoionization cross section of SH, and therein, the S₂ mass signals were even more intense than that of SH (Hrodmarsson et al. 2019a). This is due both to the fast recombination of S atoms and S₂ having a large PI cross section, that is to say, on par with SH. The S₂ cross

section is thus scaled to match the intensity of the SH cross section.

### 3.26. SiH

The photodissociation cross section of SiH has been obtained in the previous database update from the theoretical work by Lewerenz et al. (1983a,b). This cross section is here unchanged. The photoionization efficiency of SiH was recently measured by Chen et al. (2022) and to obtain the photoionization cross section this curve has been scaled to the absolute cross sections of silane and disilane which have been measured to be around 100 Mb between 11 and 14 eV (Kameta et al. 1998).

### 3.27. HF

Between this update and the previous one (Heays et al. 2017), another molecule was added to the database, namely HF. An absolute photoabsorption cross section for the continuum A–X absorption was recorded between 112 and 145 nm (Nee et al. 1985), and the entire VUV photoabsorption spectrum is measured by electron-energy-loss spectroscopy by Hitchcock et al. (1984) but with a two times greater absolute magnitude for the A–X transition. Subsequent calculations of the A–X transition (Brown & Balint-Kurti 2000a,b) clearly favor the absolute magnitude (and absorption) profile of the A–X measurement by Nee et al. (1985). Here, the entire spectrum of Hitchcock et al. (1984) was scaled down to match this (by a factor of 0.53) and the photoabsorption recorded by Nee et al. (1985) has been extrapolated linearly from 145 to 165 nm to approximately match the point where the calculated cross sections become zero (Brown & Balint-Kurti 2000a,b).

A photoionization yield measured by Berkowitz et al. (1971) was rescaled by a factor of $1.47 \times 10^{-17}$ to match the cross section of Hitchcock et al. (1984, itself already rescaled) at its shortest wavelength (62.5 nm). It was assumed 100% for this wavelength and shorter, which is roughly consistent with the branching ratios measured by Carnovale et al. (1981).

The overall uncertainty of the photodissociation and photoionization cross sections was judged to be about 30%, but the recent aforementioned ab initio calculations of the photodissociation cross sections of both HF and HCl appear to indicate that the uncertainty of the photodissociation cross section is closer to 10% (Pezzella et al. 2022; Qin et al. 2022).

## 4. Discussion

The relevance of the updated cross sections may have significant implications for our understanding of VUV-driven photoprocesses, but these may be quite species dependent. In some cases, newly measured cross sections reduced the uncertainty of previous inclusions, but in others they present completely new additions whose influence have not come to light yet.

In the previous entry of the database website, the $H_3^+$ cross section page was erroneously missing although the cross sections themselves were available in the database. This has now been rectified but here we explored a bit further the photodissociation cross section of $H_3^+$ in the context of the work of Petrignani et al. (2010) which indicated that the photodissociation of $H_3^+$ occurs at significantly longer wavelengths than was previously found by ab initio methods. We consider the effects to photorates by constructing a baseline to the cross section that accounts for the measured values. Particularly startling is the increase in the dissociation rate under a solar radiation field
(Drury & Moule 1982) but a more extensive absorption spectrum utilizing synchrotron radiation with higher resolution was recorded up to 130 nm (Chiang & Lin 2005). The latter measurements included ab initio calculations which gave oscillator strengths which helped scale the maxima of the absorption spectrum to the previously measured absolute cross sections. It is worth mentioning the theoretical efforts the ab initio calculations were based on which include many of the electronically excited states of H₂CS (Hachey & Grein 1995a,b).

A photoelectron spectrum of H₂CS was obtained via pyrolysis of CH₃SSCH₃ recorded by Kroto & Suffolk (1972). Although H₂S and CS₂ were also formed and visible in the PES, they can easily be subtracted such that the photoionization efficiency could be obtained by integrating the low-resolution PES and thus excluding the contributions from CS₂ and H₂S. The maximum was then scaled such that the scale of the cross section was similar to other sulfur containing molecules whose cross section has been measured in absolute terms, akin to what has been done with other carbon-based species.

The photodissociation of H₂CS has been subject to several experimental and theoretical studies and as a matter of fact, H₂CS has a benchmark status in theoretical studies because of the complex intersystem crossing dynamics involved in the excited states that partake in the photodissociation process (Zhang et al. 2021).

### 3.25. S₂ (disulfur, sulfur dimer)

The previous photodissociation cross section was made from a combination of experimental and theoretical works (Smith & Liszt 1971; Pradhan & Partridge 1996; Wheeler et al. 1998; Frederix et al. 2009). Recently, the absolute photoabsorption cross sections of the predissociative B–X system of S₂ has been measured in absolute terms by Stark et al. (2018) at two temperatures using the Fourier transform absorption cell at the DESIRS beamline at SOLEIL (de Oliveira et al. 2011, 2016). These measurements were accompanied by a comprehensive coupled-channel model describing the predissociative nature of the B–X system (Lewis et al. 2018). S₂ vapor was produced via an H₂S precursor gas in a radio frequency discharge for measurements at 370 K, or from solid elemental sulfur for spectra recorded at 823 K. These measurements have more recently been replicated computationally by Gomez et al. (in prep.). They calculated the absorption cross sections well below the dissociation threshold which has been measured as 280.6 nm by Frederix et al. (2009). Included in the database is the computational cross section which replicates the measurements at 370 K. The photoabsorption cross section corresponding to absorption by the B–X system below the dissociation threshold is included in the photoabsorption cross section available in the database online. It should be noted that the differences in the photodissociation rates from the measurements at the two temperatures (using the radiation fields in this work) were negligible.

The photoionization cross section of S₂ was previously made by scaling the photoionization efficiency curve measured by Liao & Ng (1986). Recently, this curve has been measured with higher resolution which has allowed assignments of multiple autoionizing resonances present in the total ion yield (Hrodmarsson et al. 2021). The total ion yield of S₂ was recorded in the same experiment which measured the absolute photoionization cross section of SH, and therein, the S₂ mass signals were even more intense than that of SH (Hrodmarsson et al. 2019a). This is due both to the fast recombination of S atoms and S₂ having a large PI cross section, that is to say, on par with SH. The S₂ cross

section is thus scaled to match the intensity of the SH cross section.

### 3.26. SiH

The photodissociation cross section of SiH has been obtained in the previous database update from the theoretical work by Lewerenz et al. (1983a,b). This cross section is here unchanged. The photoionization efficiency of SiH was recently measured by Chen et al. (2022) and to obtain the photoionization cross section this curve has been scaled to the absolute cross sections of silane and disilane which have been measured to be around 100 Mb between 11 and 14 eV (Kameta et al. 1998).

### 3.27. HF

Between this update and the previous one (Heays et al. 2017), another molecule was added to the database, namely HF. An absolute photoabsorption cross section for the continuum A–X absorption was recorded between 112 and 145 nm (Nee et al. 1985), and the entire VUV photoabsorption spectrum is measured by electron-energy-loss spectroscopy by Hitchcock et al. (1984) but with a two times greater absolute magnitude for the A–X transition. Subsequent calculations of the A–X transition (Brown & Balint-Kurti 2000a,b) clearly favor the absolute magnitude (and absorption) profile of the A–X measurement by Nee et al. (1985). Here, the entire spectrum of Hitchcock et al. (1984) was scaled down to match this (by a factor of 0.53) and the photoabsorption recorded by Nee et al. (1985) has been extrapolated linearly from 145 to 165 nm to approximately match the point where the calculated cross sections become zero (Brown & Balint-Kurti 2000a,b).

A photoionization yield measured by Berkowitz et al. (1971) was rescaled by a factor of $1.47 \times 10^{-17}$ to match the cross section of Hitchcock et al. (1984, itself already rescaled) at its shortest wavelength (62.5 nm). It was assumed 100% for this wavelength and shorter, which is roughly consistent with the branching ratios measured by Carnovale et al. (1981).

The overall uncertainty of the photodissociation and photoionization cross sections was judged to be about 30%, but the recent aforementioned ab initio calculations of the photodissociation cross sections of both HF and HCl appear to indicate that the uncertainty of the photodissociation cross section is closer to 10% (Pezzella et al. 2022; Qin et al. 2022).

## 4. Discussion

The relevance of the updated cross sections may have significant implications for our understanding of VUV-driven photoprocesses, but these may be quite species dependent. In some cases, newly measured cross sections reduced the uncertainty of previous inclusions, but in others they present completely new additions whose influence have not come to light yet.

In the previous entry of the database website, the $H_3^+$ cross section page was erroneously missing although the cross sections themselves were available in the database. This has now been rectified but here we explored a bit further the photodissociation cross section of $H_3^+$ in the context of the work of Petrignani et al. (2010) which indicated that the photodissociation of $H_3^+$ occurs at significantly longer wavelengths than was previously found by ab initio methods. We consider the effects to photorates by constructing a baseline to the cross section that accounts for the measured values. Particularly startling is the increase in the dissociation rate under a solar radiation field
where the photorate increases by almost five orders of magni-
tude but, likewise, photodissociation under a TW Hya field and
cosmic-ray induced UV photons increases by 1–2 orders of the
magnitude. This is strange because our current understanding of
the importance of H<sup>+</sup><sub>3</sub> chemistry in, for instance, protoplanetary
disks where H<sup>+</sup><sub>3</sub>-driven chemistry is used to identify and locate
CO and N<sub>2</sub> snowlines (van 't Hoff et al. 2017, 2018, 2022) does
not imply that current photorates of H<sup>+</sup><sub>3</sub> are poorly constrained.
Likewise, H<sup>+</sup><sub>3</sub> abundances in diffuse clouds where H<sup>+</sup><sub>3</sub> has been
used to constrain the cosmic ray ionization rate do not necessar-
ily imply such errors either (Indriolo 2012; Padovani et al. 2013).
However, further experimental work into the photodissociation
of H<sup>+</sup><sub>3</sub> would be of great interest.

The photodissociation and photoionization cross sections of multiple hydrocarbon species have been updated in this work. Photoionization cross sections have been added to C<sub>2</sub>H, l-C<sub>3</sub>H, c-C<sub>3</sub>H, HC<sub>3</sub>H, c-C<sub>3</sub>H<sub>2</sub>, and new hydrocarbons have been added from scratch such as C<sub>2</sub>H<sub>3</sub>, C<sub>2</sub>H<sub>5</sub> and C<sub>3</sub>H<sub>3</sub>. These hydrocarbons as well as some of their ions have been detected in various environments such as cold molecular clouds (Thaddeus et al. 1985a,b; Yamamoto et al. 1987; Brünken et al. 2014; Agúndez et al. 2021), protostellar envelopes (Murillo et al. 2018; van der Wiel et al. 2019), protoplanetary disks (Dutrey et al. 1997; Qi et al. 2013; Bergin et al. 2016), PDRs (Pety et al. 2012; Brünken et al. 2014), evolved carbon stars (Thaddeus et al. 1985a), and in the comet 67P (Beth et al. 2020), so understanding and having proper quantifications of their VUV-photoprocesses is important. For some of these species such as C<sub>2</sub>H<sub>3</sub> and C<sub>2</sub>H<sub>5</sub>, the photodissociation cross sections have never been measured or calculated to the best of our knowledge and so we include absorption measurements and draw some tentative conclusions about what their cross sections look like from the wealth of photodissociation dynamics investigations that have been performed at discrete wavelengths.

The photoionization (or photodetachment) cross sections of the hydrocarbon anions C₂H⁻, C₄H⁻, and C₆H⁻ are also included for the first time, but anions have been receiving greater attention in recent years (Millar et al. 2017). These anions have been detected in TMC-1 (McCarthy et al. 2006), the envelope of IRC +10216 (Cernicharo et al. 2007; Agúndez et al. 2010), the protostellar source L1527 (Agúndez et al. 2008; Sakai et al. 2008), the Lupus-1A starless core (Sakai et al. 2010), various star-forming, prestellar, and quiescent cores (Cordiner et al. 2011, 2013), and perhaps surprisingly, in the atmosphere of Titan with Cassini (Cravens et al. 2006; Vuitton et al. 2006; Coates et al. 2007). The chemistry of these anions has been modeled, but without the inclusion of absolute measurements of the photodetachment cross sections (Desai et al. 2017; Mukundan & Bhardwaj 2018). It is important to properly constrain these photodetachment rates as, for instance, it has been observed that the abundance of C₂H⁻ is vanishingly small in comparison to C₂H in IRC +10216 (Agúndez et al. 2010). This could likely be due to large C₂H⁻ photorates (Table 5), particularly in comparison to photodestruction rates of C₂H (Table 4) which are on average 1–2 orders of magnitude smaller than that of C₂H⁻. Indeed, in the study of CN⁻, it is suggested that VUV photodetachment is the most important destruction mechanism of anions in circumstellar envelopes (Kumar et al. 2013).

In terms of oxygen-based species, the photoionization cross sections of OH and HO₂ are included for the first time. The maximum of the OH cross section can be found around 30 Mb which is similar to the maxima of the photoionization cross sections of O₂ toward short wavelengths and the maximum of the H₂O₂ cross section around 90 nm previously included in the database

(Heays et al. 2017). Curiously, the recently measured absolute cross section of the HO₂ radical is measured with a somewhat smaller maximum below 10 Mb. It is noteworthy that the measurements of Dodson et al. (2015) only extend to 12 eV (103 nm) and from there a straight line is assumed for the cross section toward shorter wavelengths. It is entirely possible that the cross section is larger at shorter wavelengths so below 100 nm the included cross section presents a likely lower limit to the cross section. The HO₂ radical is an elusive intermediate in interstellar solid water chemistry on dust grains (Hama & Watanabe 2013), and has so far only been detected in the ρ Oph A cloud (Parise et al. 2012) which is where gas-phase O₂ was previously detected (Larsson et al. 2007). This strengthens the case of HO₂ as an indicator of gas-grain chemistry (Agúndez & Wakelam 2013; van Dishoeck et al. 2013).

The absolute measurement of the cross section of NH₂ mea-
sured by Harper et al. (2021) included here shows that the
rates of photoionization were previously overestimated by a
factor of approximately 2. The radical presents a bit of a mys-
tery because models of dark cold clouds generally predict the
NH₂ abundance to be higher than NH, but observations of
the cold envelope of IRAS 16293-2422 have shown the abun-
dance to be inverted (Hily-Blant et al. 2010). Interestingly, to
explain the NH:NH₂:NH₃ ratio of 1:10:100 in Sgr B2, invoked
PDR chemistry and/or shock chemistry were invoked to explain
these abundances (Goicoechea et al. 2004). The updated high-
accuracy cross section of NH₂ could help shed some more
light about its interstellar abundances. Concerning protoplane-
tary disks, the nitrogen chemistry is sensitive to whether you start
out with greater abundances of NH₃ or N₂. If NH₃ is more abun-
dant, then a higher abundance of N-bearing species are expected
in the midplane which could enhance the importance of NH₂ as
a reactive intermediate (Walsh et al. 2015).

Constraining the photorates of HNC is of great importance as the abundance ratio of HNC and its isomer HCN is an important chemical clock. Namely, the HNC/HCN ratio increases toward more advanced stages due the HNC isomer being more prone to destruction at higher temperatures (Jin et al. 2015). This is achieved through neutral conversion of HNC to HCN via a transition state with a barrier of 46.1 kJ mol⁻¹ or reactions with atomic H followed by elimination of H (Talbi & Ellinger 1996). As the HNC/HCN line ratio is also robust in planetary nebulae it is important to realize that the rate of VUV-photoprocesses of HNC do not necessarily exceed those of HCN. In fact, comparisons of the photorates of HNC included here and those of HCN in the database reveal that HNC is slightly less prone to destruction under VUV. This places recent results by Bublitz et al. (2022) into some perspective as they found that the HNC/HCN ratio is anticorrelated with radial distance from the central star and, furthermore, it appears to be anticorrelated with UV emission over four orders of magnitude in incident flux. Hence, it is very important to characterize these photorates so that the HNC/HCN ratio could still be reliably used for regions experiencing harsher radiation fields, such as different layers of protoplanetary disks (Long et al. 2021).

With the recent detection of DME in a protoplanetary disk (Brüken et al. 2022), it is clear that accounting for photorates is presenting a new challenge for models. Although VUV photorates of multiple complex molecules are already known, it is also true that VUV photodissociation is a multiplex phenomenon for complex molecules and acquiring accurate branching ratios of multiple dissociation channels is a monumental experimental and theoretical challenge for the coming decade. As an example, a relatively small molecule such as methane (CH₄) has at
where the photorate increases by almost five orders of magni-
tude but, likewise, photodissociation under a TW Hya field and
cosmic-ray induced UV photons increases by 1–2 orders of the
magnitude. This is strange because our current understanding of
the importance of $H_3^+$ chemistry in, for instance, protoplanetary
disks where $H_3^+$-driven chemistry is used to identify and locate
CO and $N_2$ snowlines (van't Hoff et al. 2017, 2018, 2022) does
not imply that current photorates of $H_3^+$ are poorly constrained.
Likewise, $H_3^+$ abundances in diffuse clouds where $H_3^+$ has been
used to constrain the cosmic ray ionization rate do not necessar-
ily imply such errors either (Indriolo 2012; Padovani et al. 2013).
However, further experimental work into the photodissociation
of $H_3^+$ would be of great interest.

The photodissociation and photoionization cross sections of multiple hydrocarbon species have been updated in this work. Photoionization cross sections have been added to C₂H, l-C₃H, c-C₃H, HC₃H, c-C₃H₂, and new hydrocarbons have been added from scratch such as C₂H₃, C₂H₅ and C₃H₃. These hydrocarbons as well as some of their ions have been detected in various environments such as cold molecular clouds (Thaddeus et al. 1985a,b; Yamamoto et al. 1987; Brünken et al. 2014; Agúndez et al. 2021), protostellar envelopes (Murillo et al. 2018; van der Wiel et al. 2019), protoplanetary disks (Dutrey et al. 1997; Qi et al. 2013; Bergin et al. 2016), PDRs (Pety et al. 2012; Brünken et al. 2014), evolved carbon stars (Thaddeus et al. 1985a), and in the comet 67P (Beth et al. 2020), so understanding and having proper quantifications of their VUV-photoprocesses is important. For some of these species such as C₂H₃ and C₂H₅, the photodissociation cross sections have never been measured or calculated to the best of our knowledge and so we include absorption measurements and draw some tentative conclusions about what their cross sections look like from the wealth of photodissociation dynamics investigations that have been performed at discrete wavelengths.

The photoionization (or photodetachment) cross sections of the hydrocarbon anions C₂H⁻, C₄H⁻, and C₆H⁻ are also included for the first time, but anions have been receiving greater attention in recent years (Millar et al. 2017). These anions have been detected in TMC-1 (McCarthy et al. 2006), the envelope of IRC +10216 (Cernicharo et al. 2007; Agúndez et al. 2010), the protostellar source L1527 (Agúndez et al. 2008; Sakai et al. 2008), the Lupus-1A starless core (Sakai et al. 2010), various star-forming, prestellar, and quiescent cores (Cordiner et al. 2011, 2013), and perhaps surprisingly, in the atmosphere of Titan with Cassini (Cravens et al. 2006; Vuitton et al. 2006; Coates et al. 2007). The chemistry of these anions has been modeled, but without the inclusion of absolute measurements of the photodetachment cross sections (Desai et al. 2017; Mukundan & Bhardwaj 2018). It is important to properly constrain these photodetachment rates as, for instance, it has been observed that the abundance of C₂H⁻ is vanishingly small in comparison to C₂H in IRC +10216 (Agúndez et al. 2010). This could likely be due to large C₂H⁻ photorates (Table 5), particularly in comparison to photodestruction rates of C₂H (Table 4) which are on average 1–2 orders of magnitude smaller than that of C₂H⁻. Indeed, in the study of CN⁻, it is suggested that VUV photodetachment is the most important destruction mechanism of anions in circumstellar envelopes (Kumar et al. 2013).

In terms of oxygen-based species, the photoionization cross sections of OH and HO₂ are included for the first time. The maximum of the OH cross section can be found around 30 Mb which is similar to the maxima of the photoionization cross sections of O₂ toward short wavelengths and the maximum of the H₂O₂ cross section around 90 nm previously included in the database

(Heays et al. 2017). Curiously, the recently measured absolute cross section of the HO₂ radical is measured with a somewhat smaller maximum below 10 Mb. It is noteworthy that the measurements of Dodson et al. (2015) only extend to 12 eV (103 nm) and from there a straight line is assumed for the cross section toward shorter wavelengths. It is entirely possible that the cross section is larger at shorter wavelengths so below 100 nm the included cross section presents a likely lower limit to the cross section. The HO₂ radical is an elusive intermediate in interstellar solid water chemistry on dust grains (Hama & Watanabe 2013), and has so far only been detected in the ρ Oph A cloud (Parise et al. 2012) which is where gas-phase O₂ was previously detected (Larsson et al. 2007). This strengthens the case of HO₂ as an indicator of gas-grain chemistry (Agúndez & Wakelam 2013; van Dishoeck et al. 2013).

The absolute measurement of the cross section of NH₂ mea-
sured by Harper et al. (2021) included here shows that the
rates of photoionization were previously overestimated by a
factor of approximately 2. The radical presents a bit of a mis-
tery because models of dark cold clouds generally predict the
NH₂ abundance to be higher than NH, but observations of
the cold envelope of IRAS 16293-2422 have shown the abun-
dance to be inverted (Hily-Blant et al. 2010). Interestingly, to
explain the NH:NH₂:NH₃ ratio of 1:10:100 in Sgr B2, invoked
PDR chemistry and/or shock chemistry were invoked to explain
these abundances (Goicoechea et al. 2004). The updated high-
accuracy cross section of NH₂ could help shed some more
light about its interstellar abundances. Concerning protoplane-
tary disks, the nitrogen chemistry is sensitive to whether you start
out with greater abundances of NH₃ or N₂. If NH₃ is more abun-
dant, then a higher abundance of N-bearing species are expected
in the midplane which could enhance the importance of NH₂ as
a reactive intermediate (Walsh et al. 2015).

Constraining the photorates of HNC is of great importance as the abundance ratio of HNC and its isomer HCN is an important chemical clock. Namely, the HNC/HCN ratio increases toward more advanced stages due the HNC isomer being more prone to destruction at higher temperatures (Jin et al. 2015). This is achieved through neutral conversion of HNC to HCN via a transition state with a barrier of 46.1 kJ mol⁻¹ or reactions with atomic H followed by elimination of H (Talbi & Ellinger 1996). As the HNC/HCN line ratio is also robust in planetary nebulae it is important to realize that the rate of VUV-photoprocesses of HNC do not necessarily exceed those of HCN. In fact, comparisons of the photorates of HNC included here and those of HCN in the database reveal that HNC is slightly less prone to destruction under VUV. This places recent results by Bublitz et al. (2022) into some perspective as they found that the HNC/HCN ratio is anticorrelated with radial distance from the central star and, furthermore, it appears to be anticorrelated with UV emission over four orders of magnitude in incident flux. Hence, it is very important to characterize these photorates so that the HNC/HCN ratio could still be reliably used for regions experiencing harsher radiation fields, such as different layers of protoplanetary disks (Long et al. 2021).

With the recent detection of DME in a protoplanetary disk (Brüken et al. 2022), it is clear that accounting for photorates is presenting a new challenge for models. Although VUV photorates of multiple complex molecules are already known, it is also true that VUV photodissociation is a multiplex phenomenon for complex molecules and acquiring accurate branching ratios of multiple dissociation channels is a monumental experimental and theoretical challenge for the coming decade. As an example, a relatively small molecule such as methane (CH₄) has at
least seven different photodissociation and several more disso-
ciative photoionization channels which are known in the VUV
(Gans et al. 2011a). By doubling the number of carbon atoms
and investigating ethane (CH3CH3), the number of photodissoci-
ation channels alone that are accessible below the Lyman-α limit
is at least seventeen (Chang et al. 2020). Thus, in the future, to
characterize the VUV-driven processes of complex molecules in
space photodissociation and photoionization cross sections need
to be divided according to the branching ratios of different chan-
nels that produce different products. This kind of separation is
already available in the database for abundant molecules such
as H2O and NH3 (Heays et al. 2017), but significant progress has
already been made in measuring absolute branching ratios of dif-
ferent photodissociation processes in small molecules. Namely,
the branching ratios of several fragmentation channels from pre-
dissociative Rydberg states have been measured in CO (Gao et al.
2011a, 2012, 2013, 2020; Shi et al. 2018; Chi et al. 2020), N2
(Gao et al. 2011b; Song et al. 2016; Shi et al. 2017), and CO2 (Lu
et al. 2014).

Besides molecular complexity, interstellar sulfur chemistry
has been receiving more attention recently, particularly in the
light of recent detections of numerous complex sulfur-bearing
molecules in the ISM (Fuente et al. 2017; Agúndez et al.
2018; Cernicharo et al. 2018, 2021b,c,d; Cabezas et al. 2022;
Fuentetaja et al. 2022), protostellar systems (Blake et al. 1994;
Caux et al. 2011; Majumdar et al. 2016; Martín-Doménech et al.
2016; Drozdovskaya et al. 2018), as well as the detection of H2S,
H2CS and CS in protoplanetary disks (Dutrey et al. 1997; Phuong
et al. 2018; Le Gal et al. 2019). Here we update three fundamen-
tal sulfur bearing molecules, SH, S2 and CS and add the cross
sections of H2CS, which has been used to derive temperature
structures in protoplanetary disks (van 't Hoff et al. 2020).

Both SH⁺ and SH have observed in low-density diffuse
clouds (Menten et al. 2011; Godard et al. 2012; Neufeld et al.
2012, 2015). Hence, we have added here the measured absolute
photoionization cross section of the SH radical (Hrodmarsson
et al. 2019a). It shows that previous photoionization rates of SH
were severely underestimated by 1–2 orders of magnitude which
has prompted us to rescale more recent measurements of the pho-
toionization efficiency of S2 (Hrodmarsson et al. 2021). This is
important to establish because sulfur hydride chemistry in space
is quite unusual because none of simplest sulfur species, S, S⁺,
SH, SH⁺, and H₂S⁺ can react exothermically with H₂(ν = 0)
(Goicoechea et al. 2021) and so to ignite sulfur chemistry the
gas needs to be UV-irradiated followed by intense heat (Zanchet
et al. 2013, 2019). Both of SH and S₂ are also expected to be
important heating components of atmospheres of Hot Jupiters
(Zahnle et al. 2009), and both have been observed in our Solar
System; SH in the solar atmosphere (Berdyugina & Livingston
2002), and S₂ on Jupiter (Noll et al. 1995), in volcanic plumes on
Io (Spencer et al. 2000; Jessup et al. 2007), and cometary comae
(Ahearn et al. 1983; Kim et al. 2003).

The photodissociation and photoionization cross sections of
CS have also been updated. Implementing the photodissociation
cross sections computed by Xu et al. (2019) requires bringing
up the role resolution plays when it comes to interpolating mea-
sured and computed cross sections for numerical integrations.
Throughout this paper and presented in the database, all cross
sections and radiation fields are computed on a 0.001 nm grid.
The calculated cross section of CS, however, contains a myr-
iad of finely resolved spectral features with FWHM that could
only be fully captured using a resolution better than 0.00004 nm.
Hence, some spectral features were left out by using a larger grid
which resulted in slightly smaller photorates (smaller than 10%)

which is still better than the 20% accuracy limit required for an
A+ rating.

One interesting finding here are the computed photodissocia-
tion rates for different radiation fields of CS (Table 27). Namely,
the radiation fields whose intensities are greater toward shorter
wavelengths and more discrete in nature, give smaller photodis-
sociation rates while the photorates of continuum radiation fields
such as ISRF, are larger by a factor of few. These differences
arise from the previous photodissociation cross section being
overestimated by up to an order of magnitude between 116 and
125 nm, approximately. This results in the photorates under
radiation fields with large fluxes at shorter wavelengths (par-
ticularly the Lyman-α line), being significantly smaller than the
previously included cross section.

Xu et al. (2019) also computed the CS photodissociation cross section for higher temperatures up to 500 K. Although the difference in the computed photodissociation rates from 20 to 500 K was negligible in the case of CS, it is important to account for temperature effects in molecules that can be abundant components in exoplanetary atmospheres. Exoplanets and in particular Hot Jupiters and Hot Neptunes, require significant quantities of molecular spectroscopic data to model radiative transport in their atmospheres, interpret their spectra, and understand the underlying photo-driven chemistry to account for observed molecular abundances (Hill et al. 2013). For instance, high temperature VUV cross sections are important to chemically quantify the impact of stellar flares on exoplanetary atmosphere compositions (Venot et al. 2016), and to quantify the contribution of VUV photon-induced processes to disequilibria in atmospheric chemistry which can lead to changes in temperature profiles (Drummond et al. 2016).

It is also important to quantify the cross sections in terms
of their shielding effects in exoplanetary atmospheres. VUV
shielding of molecules such as H₂O, O₂, CO and CO₂ allows
hydrocarbon species, which exists in lower layers of the atmo-
sphere, to survive and proliferate under the shielding effects
of exoplanet atmospheres (Kawashima & Ikoma 2019). VUV-
photoprocesses can also change the atmospheric composition
down to depths of several bar in cool exoplanets, in part because
the night sides of most cool planets are shown to host photo-
chemical products transported from the day side by horizontal
advection (Baeyens et al. 2022).

Experimental work on high-temperature VUV cross sections is challenging due to the limitations presented by the materials used in absorption cells. There is ongoing experimental work addressing these challenges by, for instance, extrapolating a series of measurements beyond 800 K, like has been done for CO₂ (Venot et al. 2018a,b). There, it was shown that by including the high-temperature cross sections of CO₂ in a chemical model of a Hot Neptune-like exoplanet, the abundances of multiple species are altered, some by orders of magnitude. It will be of interest to see how other newly computed high-temperature VUV cross sections of diatomics such as HCl, HF, and others (Pezzella et al. 2021, 2022) will influence the results from chemical models of exoplanet atmospheres.

Finally, the photoionization cross section of SiH is included
here for the first time. As silicates are widely observed to be
among the most abundant and important components of refrac-
tory materials in the ISM (van Dishoeck 2004), it is sensible
that the chemistry of silicon is found to be significantly affected
by depletion of Si onto grains (Herbst et al. 1989). SiH has
been long observed in the spectrum of our Sun (Babcock 1945;
Sauval 1969) and various cool stars (Merrill 1955), and it is pre-
dicted to be present in high-pressure exoplanetary atmospheres
least seven different photodissociation and several more disso-
ciative photoionization channels which are known in the VUV
(Gans et al. 2011a). By doubling the number of carbon atoms
and investigating ethane (CH3CH3), the number of photodissoci-
ation channels alone that are accessible below the Lyman-α limit
is at least seventeen (Chang et al. 2020). Thus, in the future, to
characterize the VUV-driven processes of complex molecules in
space photodissociation and photoionization cross sections need
to be divided according to the branching ratios of different chan-
nels that produce different products. This kind of separation is
already available in the database for abundant molecules such
as H2O and NH3 (Heays et al. 2017), but significant progress has
already been made in measuring absolute branching ratios of dif-
ferent photodissociation processes in small molecules. Namely,
the branching ratios of several fragmentation channels from pre-
dissociative Rydberg states have been measured in CO (Gao et al.
2011a, 2012, 2013, 2020; Shi et al. 2018; Chi et al. 2020), N2
(Gao et al. 2011b; Song et al. 2016; Shi et al. 2017), and CO2 (Lu
et al. 2014).

Besides molecular complexity, interstellar sulfur chemistry
has been receiving more attention recently, particularly in the
light of recent detections of numerous complex sulfur-bearing
molecules in the ISM (Fuente et al. 2017; Agúndez et al.
2018; Cernicharo et al. 2018, 2021b,c,d; Cabezas et al. 2022;
Fuentetaja et al. 2022), protostellar systems (Blake et al. 1994;
Caux et al. 2011; Majumdar et al. 2016; Martín-Doménech et al.
2016; Drozdovskaya et al. 2018), as well as the detection of H2S,
H2CS and CS in protoplanetary disks (Dutrey et al. 1997; Phuong
et al. 2018; Le Gal et al. 2019). Here we update three fundamen-
tal sulfur bearing molecules, SH, S2 and CS and add the cross
sections of H2CS, which has been used to derive temperature
structures in protoplanetary disks (van 't Hoff et al. 2020).

Both SH⁺ and SH have observed in low-density diffuse
clouds (Menten et al. 2011; Godard et al. 2012; Neufeld et al.
2012, 2015). Hence, we have added here the measured absolute
photoionization cross section of the SH radical (Hrodmarsson
et al. 2019a). It shows that previous photoionization rates of SH
were severely underestimated by 1–2 orders of magnitude which
has prompted us to rescale more recent measurements of the pho-
toionization efficiency of S2 (Hrodmarsson et al. 2021). This is
important to establish because sulfur hydride chemistry in space
is quite unusual because none of simplest sulfur species, S, S⁺,
SH, SH⁺, and H₂S⁺ can react exothermically with H₂(ν = 0)
(Goicoechea et al. 2021) and so to ignite sulfur chemistry the
gas needs to be UV-irradiated followed by intense heat (Zanchet
et al. 2013, 2019). Both of SH and S₂ are also expected to be
important heating components of atmospheres of Hot Jupiters
(Zahnle et al. 2009), and both have been observed in our Solar
System; SH in the solar atmosphere (Berdyugina & Livingston
2002), and S₂ on Jupiter (Noll et al. 1995), in volcanic plumes on
Io (Spencer et al. 2000; Jessup et al. 2007), and cometary comae
(Ahearn et al. 1983; Kim et al. 2003).

The photodissociation and photoionization cross sections of
CS have also been updated. Implementing the photodissociation
cross sections computed by Xu et al. (2019) requires bringing
up the role resolution plays when it comes to interpolating mea-
sured and computed cross sections for numerical integrations.
Throughout this paper and presented in the database, all cross
sections and radiation fields are computed on a 0.001 nm grid.
The calculated cross section of CS, however, contains a myr-
iad of finely resolved spectral features with FWHM that could
only be fully captured using a resolution better than 0.00004 nm.
Hence, some spectral features were left out by using a larger grid
which resulted in slightly smaller photorates (smaller than 10%)

which is still better than the 20% accuracy limit required for an
A+ rating.

One interesting finding here are the computed photodissocia-
tion rates for different radiation fields of CS (Table 27). Namely,
the radiation fields whose intensities are greater toward shorter
wavelengths and more discrete in nature, give smaller photodis-
sociation rates while the photorates of continuum radiation fields
such as ISRF, are larger by a factor of few. These differences
arise from the previous photodissociation cross section being
overestimated by up to an order of magnitude between 116 and
125 nm, approximately. This results in the photorates under
radiation fields with large fluxes at shorter wavelengths (par-
ticularly the Lyman-α line), being significantly smaller than the
previously included cross section.

Xu et al. (2019) also computed the CS photodissociation cross section for higher temperatures up to 500 K. Although the difference in the computed photodissociation rates from 20 to 500 K was negligible in the case of CS, it is important to account for temperature effects in molecules that can be abundant components in exoplanetary atmospheres. Exoplanets and in particular Hot Jupiters and Hot Neptunes, require significant quantities of molecular spectroscopic data to model radiative transport in their atmospheres, interpret their spectra, and understand the underlying photo-driven chemistry to account for observed molecular abundances (Hill et al. 2013). For instance, high temperature VUV cross sections are important to chemically quantify the impact of stellar flares on exoplanetary atmosphere compositions (Venot et al. 2016), and to quantify the contribution of VUV photon-induced processes to disequilibria in atmospheric chemistry which can lead to changes in temperature profiles (Drummond et al. 2016).

It is also important to quantify the cross sections in terms
of their shielding effects in exoplanetary atmospheres. VUV
shielding of molecules such as H₂O, O₂, CO and CO₂ allows
hydrocarbon species, which exists in lower layers of the atmo-
sphere, to survive and proliferate under the shielding effects
of exoplanet atmospheres (Kawashima & Ikoma 2019). VUV-
photoprocesses can also change the atmospheric composition
down to depths of several bar in cool exoplanets, in part because
the night sides of most cool planets are shown to host photo-
chemical products transported from the day side by horizontal
advection (Baeyens et al. 2022).

Experimental work on high-temperature VUV cross sections is challenging due to the limitations presented by the materials used in absorption cells. There is ongoing experimental work addressing these challenges by, for instance, extrapolating a series of measurements beyond 800 K, like has been done for CO₂ (Venot et al. 2018a,b). There, it was shown that by including the high-temperature cross sections of CO₂ in a chemical model of a Hot Neptune-like exoplanet, the abundances of multiple species are altered, some by orders of magnitude. It will be of interest to see how other newly computed high-temperature VUV cross sections of diatomics such as HCl, HF, and others (Pezzella et al. 2021, 2022) will influence the results from chemical models of exoplanet atmospheres.

Finally, the photoionization cross section of SiH is included
here for the first time. As silicates are widely observed to be
among the most abundant and important components of refrac-
tory materials in the ISM (van Dishoeck 2004), it is sensible
that the chemistry of silicon is found to be significantly affected
by depletion of Si onto grains (Herbst et al. 1989). SiH has
been long observed in the spectrum of our Sun (Babcock 1945;
Sauval 1969) and various cool stars (Merrill 1955), and it is pre-
dicted to be present in high-pressure exoplanetary atmospheres
that contain both SiH₄ and SiO in the presence of H₂O (Visscher et al. 2010). While silane (SiH₄) has been detected in the gas surrounding IRC +10216 (Goldhaber & Betz 1984), the interstellar presence of SiH has so far merely been hinted at (Walmsley et al. 1999), but it may still play an important role as intermediate in the chemistry leading to SiS via reactions with atomic or diatomic sulfur (Rosi et al. 2018).

## 5. Conclusions

The Leiden VUV cross section database has been updated and expanded with new photodissociation and photoionization cross sections of molecules of varied astronomical interest, accompanied by uncertainty estimates. The cross sections are used to compute rates of photodissociation and photoionization in several different radiation fields and are compared with previous database entries where appropriate. Many of the new cross sections have been obtained thanks to experimental and theoretical advances which have been detailed. Thanks to these advances, the newly updated cross sections generally provide excellent constraints (generally better than 30%) to the computed photorates.

Also accompanied and updated in the database are photorates computed assuming dust and line shielding and shielding functions that are suitable for use in astrochemical models that account for VUV photoprocesses, which are not easily parametrized.

The cross sections and derived data for now a total of 116 atoms and molecules are available from the Leiden VUV cross section database. These are provided in both a binary format, explicitly including all cross section features on a dense wavelength grid, and sparser text format that is more suitable for rapid calculation in a continuum radiation field. The database update includes 14 new species and updates to 16 previous entries.

*Acknowledgements.* Thanks to Alan Heays for assistance with the database update and computations, and Arthur Bosman for useful discussions. Thanks to Séverine Boyé-Péronne, Bérenger Gans, and Jean-Christophe Loison for providing the photoionization efficiencies and threshold photoelectron spectra of CH, C₂, C₂H, C₂H₃, C₂H₅, HNC and SiH. Thanks to Gustavo Garcia for the photoionization efficiencies and the separated TPES of I-C₃H, c-C₃H, HC₃H, and c-C₃H₂. Thanks to Zhongxing Xu and Kyle Crabtree for providing the photodissociation cross sections of CS. Thanks to Iouli Gordon, Robert Hargreaves, and Fran Skinner for providing the photoabsorption cross sections of S₂. This work was supported by the Programme National "Physique et Chimie du Milieu Interstellaire" (PCMI) of CNRS/INSU with INC/INP co-funded by CEA and CNES.

## References

* Aguado, A., Roncero, O., Zanchet, A., Agúndez, M., & Cernicharo, J. 2017, ApJ, 838, 33

* Agúndez, M., & Wakelam, V. 2013, Chem. Rev., 113, 8710

* Agúndez, M., Cernicharo, J., Guelin, M., et al. 2008, A&A, 478, L19

* Agúndez, M., Cernicharo, J., Guelin, M., et al. 2010, A&A, 517, A2

* Agúndez, M., Cernicharo, J., de Vicente, P., et al. 2015, A&A, 579, A10

* Agúndez, M., Marcelino, N., Cernicharo, J., & Tafalla, M. 2018, A&A, 611, A1

* Agúndez, M., Cabezas, C., Tercero, B., et al. 2021, A&A, 647, A10

* Ahearn, M., Feldman, P., & Schleicher, D. 1983, ApJ, 274, L99

* Ahmed, M., Peterka, D. S., & Suits, A. G. 1999, J. Chem. Phys., 110, 4248

* Aikawa, Y., van Zadelhoff, G. J., van Dishoeck, E. F., & Herbst, E. 2002, A&A, 386, 622

* Armijos-Abendaño, J., Martín-Pintado, J., López, E., et al. 2020, ApJ, 895, 57

* Babcock, H. 1945, ApJ, 102, 154

* Bacalla, X. L., Linnartz, H., Cox, N. L. J., et al. 2019, A&A, 622, A31

* Baer, T., & Tuckett, R. P. 2017, Phys. Chem. Chem. Phys., 19, 9698

* Baeyens, R., Konings, T., Venot, O., Carone, L., & Decin, L. 2022, MNRAS, 512, 4877

* Barger, C. J., & Garrod, R. T. 2020, ApJ, 888, 38

* Barr, A. G., Boogert, A., De Witt, C. N., et al. 2018, ApJ, 868, L2

* Barsuhn, J., & Nesbet, R. 1978, J. Chem. Phys., 68, 2783

* Benz, A. O., Bruderer, S., van Dishoeck, E. F., et al. 2011, EAS Pub. Ser., 52, 239

* Benz, A. O., Bruderer, S., van Dishoeck, E. F., et al. 2016, A&A, 590, A105

* Berdyugina, S. V., & Livingston, W. C. 2002, A&A, 387, L6

* Bergin, E. A., Du, F., Cleeves, L. I., et al. 2016, ApJ, 831, 101

* Bergner, J. B., Öberg, K. I., Garrod, R. T., & Graninger, D. M. 2017, ApJ, 841, 120

* Bergner, J. B., Guzman, V. G., Öberg, K. I., Loomis, R. A., & Pegues, J. 2018, ApJ, 857, 69

* Bergner, J. B., Öberg, K. I., Bergin, E. A., et al. 2019, ApJ, 876, 25

* Bergner, J. B., Öberg, K. I., Guzman, V. V., et al. 2021, ApJS, 257, 11

* Berkowitz, J., Chupka, W., Guyon, P., Holloway, J., & Spohr, R. 1971, J. Chem. Phys., 54, 5165

* Best, T., Otto, R., Trippel, S., et al. 2011, ApJ, 742, 63

* Beth, A., Altwegg, K., Balsiger, H., et al. 2020, A&A, 642, A27

* Bethell, T., & Bergin, E. 2009, Science, 326, 1675

* Blake, G. A., van Dishoeck, E. F., Jansen, D. J., Groesbeck, T. D., & Mundy, L. G. 1994, ApJ, 428, 680

* Bobeldijk, M., van der Zande, W., & Kistemaker, P. 1994, Chem. Phys., 179, 125

* Bodi, A., Hemberger, P., Gerber, T., & Sztaray, B. 2012, Rev. Sci. Instrum., 83, 083105

* Boechat-Roberty, H. M., Pilling, S., & Santos, A. C. F. 2005, A&A, 438, 915

* Booth, A. S., Walsh, C., Terwisscha van Scheltinga, J., et al. 2021, Nat. Astron., 5, 684

* Borsvozszky, J., Nauta, K., Jiang, J., et al. 2021, PNAS, 118, e2113315118

* Bosman, A. D., Alarcon, F., Bergin, E. A., et al. 2021, ApJS, 257, 7

* Bovino, S., Ferrada-Chamorro, S., Lupi, A., Schleicher, D. R. G., & Caselli, P. 2020, MNRAS, 495, L7

* Brown, A., & Balint-Kurti, G. G. 2000a, J. Chem. Phys., 113, 1870

* Brown, A., & Balint-Kurti, G. G. 2000b, J. Chem. Phys., 113, 1879

* Brown, J. M., & Carrington, A. 2003, Rotational Spectroscopy of Diatomic Molecules (Cambridge University Press)

* Bruderer, S., Benz, A. O., Staeuber, P., & Doty, S. D. 2010, ApJ, 720, 1432

* Bruna, P. J., & Hirsch, G. 1987, Mol. Phys., 61, 1359

* Bruna, P., Kammer, W., & Vasudevan, K. 1975, Chem. Phys., 9, 91

* Bruna, P., Buenker, R., & Peyerimhoff, S. 1976, J. Mol. Struct., 32, 217

* Brünken, S., Kluge, L., Stoffels, A., Asvany, O., & Schlemmer, S. 2014, ApJ, 783, L4

* Brunken, N. G. C., Booth, A. S., Leemker, M., et al. 2022, A&A, 659, A29

* Bublitz, J., Kastner, J. H., Hily-Blant, P., et al. 2022, A&A, 659, A197

* Cabezas, C., Agúndez, M., Marcelino, N., et al. 2022, A&A, 657, A4

* Calahan, J. K., Bergin, E. A., & Bosman, A. D. 2022, ApJ, 934, L14

* Carnovale, F., Tseng, R., & Brion, C. 1981, J. Phys. B., 14, 4771

* Caselli, P., & Walmsley, C. M. 2001, ASP Conf. Ser., 243, 67

* Caselli, P., Walmsley, C. M., Terzieva, R., & Herbst, E. 1998, ApJ, 499, 234

* Cashion, J. 1963, J. Chem. Phys., 39, 1872

* Cataldi, G., Wu, Y., Brandeker, A., et al. 2020, ApJ, 892, 99

* Caux, E., Kahane, C., Castets, A., et al. 2011, A&A, 532, A23

* Cazzoletti, P., van Dishoeck, E. F., Visser, R., Facchini, S., & Bruderer, S. 2018, A&A, 609, A93

* Ceccarelli, C., Dominik, C., Lopez-Sepulcre, A., et al. 2014, ApJ, 790, L1

* Cecchi-Pestellini, C., & Aiello, S. 1992, MNRAS, 258, 125

* Cernicharo, J., Heras, A. M., Tielens, A. G. G. M., et al. 2001, ApJ, 546, L123

* Cernicharo, J., Guélin, M., Agúndez, M., et al. 2007, A&A, 467, L37

* Cernicharo, J., Lefloch, B., Agúndez, M., et al. 2018, ApJ, 853, L22

* Cernicharo, J., Agúndez, M., Cabezas, C., et al. 2021a, A&A, 649, L15

* Cernicharo, J., Cabezas, C., Agúndez, M., et al. 2021b, A&A, 648, L3

* Cernicharo, J., Cabezas, C., Endo, Y., et al. 2021c, A&A, 646, L3

* Cernicharo, J., Cabezas, C., Endo, Y., et al. 2021d, A&A, 650, L14

* Chang, Y., Yang, J., Chen, Z., et al. 2020, Chem. Sci., 11, 5089

* Chen, N. L., Gans, B., Hartweg, S., et al. 2022, J. Chem. Phys., 157, 014303

* Chi, X., Jiang, P., Zhu, Q., et al. 2020, ApJ, 891, 16

* Chiang, S. Y., & Lin, I. F. 2005, J. Chem. Phys., 122, 094301

* Chicharro, D. V., Poullain, S. M., Zanchet, A., et al. 2019, Chem. Sci., 10, 6494

* Cleeves, L. I., Adams, F. C., & Bergin, E. A. 2013, ApJ, 772, 5

* Cleeves, L. I., Bergin, E. A., & Adams, F. C. 2014, ApJ, 794, 123

* Cleeves, L. I., Bergin, E. A., Qi, C., Adams, F. C., & Öberg, K. I. 2015, ApJ, 799, 204

* Coates, A. J., Crary, F. J., Lewis, G. R., et al. 2007, Geophys. Res. Lett., 34, L22103

* Codella, C., Lopez-Sepulcre, A., Ohashi, S., et al. 2022, MNRAS, 515, 543

* Continetti, R. E. 2001, Annu. Rev. Phys. Chem., 52, 165
that contain both $SiH_4$ and $SiO$ in the presence of $H_2O$ (Visscher et al. 2010). While silane ($SiH_4$) has been detected in the gas surrounding IRC +10216 (Goldhaber & Betz 1984), the interstellar presence of SiH has so far merely been hinted at (Walmsley et al. 1999), but it may still play an important role as intermediate in the chemistry leading to SiS via reactions with atomic or diatomic sulfur (Rosi et al. 2018).

## 5. Conclusions

The Leiden VUV cross section database has been updated and expanded with new photodissociation and photoionization cross sections of molecules of varied astronomical interest, accompanied by uncertainty estimates. The cross sections are used to compute rates of photodissociation and photoionization in several different radiation fields and are compared with previous database entries where appropriate. Many of the new cross sections have been obtained thanks to experimental and theoretical advances which have been detailed. Thanks to these advances, the newly updated cross sections generally provide excellent constraints (generally better than 30%) to the computed photorates.

Also accompanied and updated in the database are photorates computed assuming dust and line shielding and shielding functions that are suitable for use in astrochemical models that account for VUV photoprocesses, which are not easily parametrized.

The cross sections and derived data for now a total of 116 atoms and molecules are available from the Leiden VUV cross section database. These are provided in both a binary format, explicitly including all cross section features on a dense wavelength grid, and sparser text format that is more suitable for rapid calculation in a continuum radiation field. The database update includes 14 new species and updates to 16 previous entries.

**Acknowledgements.** Thanks to Alan Heays for assistance with the database update and computations, and Arthur Bosman for useful discussions. Thanks to Séverine Boyé-Péronne, Bérenger Gans, and Jean-Christophe Loison for providing the photoionization efficiencies and threshold photoelectron spectra of CH, $C_2$, $C_2H$, $C_2H_3$, $C_2H_5$, HNC and SiH. Thanks to Gustavo Garcia for the photoionization efficiencies and the separated TPES of $I-C_3H$, $c-C_3H$, $HC_3H$, and $c-C_3H_2$. Thanks to Zhongxing Xu and Kyle Crabtree for providing the photodissociation cross sections of CS. Thanks to Iouli Gordon, Robert Hargreaves, and Fran Skinner for providing the photoabsorption cross sections of $S_2$. This work was supported by the Programme National "Physique et Chimie du Milieu Interstellaire" (PCMI) of CNRS/INSU with INC/INP co-funded by CEA and CNES.

## References

* Aguado, A., Roncero, O., Zanchet, A., Agúndez, M., & Cernicharo, J. 2017, ApJ, 838, 33

* Agúndez, M., & Wakelam, V. 2013, Chem. Rev., 113, 8710

* Agúndez, M., Cernicharo, J., Guelin, M., et al. 2008, A&A, 478, L19

* Agúndez, M., Cernicharo, J., Guelin, M., et al. 2010, A&A, 517, A2

* Agúndez, M., Cernicharo, J., de Vicente, P., et al. 2015, A&A, 579, A10

* Agúndez, M., Marcelino, N., Cernicharo, J., & Tafalla, M. 2018, A&A, 611, A1

* Agúndez, M., Cabezas, C., Tercero, B., et al. 2021, A&A, 647, A10

* Ahearn, M., Feldman, P., & Schleicher, D. 1983, ApJ, 274, L99

* Ahmed, M., Peterka, D. S., & Suits, A. G. 1999, J. Chem. Phys., 110, 4248

* Aikawa, Y., van Zadelhoff, G. J., van Dishoeck, E. F., & Herbst, E. 2002, A&A, 386, 622

* Armijos-Abendaño, J., Martín-Pintado, J., López, E., et al. 2020, ApJ, 895, 57

* Babcock, H. 1945, ApJ, 102, 154

* Bacalla, X. L., Linnartz, H., Cox, N. L. J., et al. 2019, A&A, 622, A31

* Baer, T., & Tuckett, R. P. 2017, Phys. Chem. Chem. Phys., 19, 9698

* Baeyens, R., Konings, T., Venot, O., Carone, L., & Decin, L. 2022, MNRAS, 512, 4877

* Barger, C. J., & Garrod, R. T. 2020, ApJ, 888, 38

* Barr, A. G., Boogert, A., De Witt, C. N., et al. 2018, ApJ, 868, L2

* Barsuhn, J., & Nesbet, R. 1978, J. Chem. Phys., 68, 2783

* Benz, A. O., Bruderer, S., van Dishoeck, E. F., et al. 2011, EAS Pub. Ser., 52, 239

* Benz, A. O., Bruderer, S., van Dishoeck, E. F., et al. 2016, A&A, 590, A105

* Berdyugina, S. V., & Livingston, W. C. 2002, A&A, 387, L6

* Bergin, E. A., Du, F., Cleeves, L. I., et al. 2016, ApJ, 831, 101

* Bergner, J. B., Öberg, K. I., Garrod, R. T., & Graninger, D. M. 2017, ApJ, 841, 120

* Bergner, J. B., Guzman, V. G., Öberg, K. I., Loomis, R. A., & Pegues, J. 2018, ApJ, 857, 69

* Bergner, J. B., Öberg, K. I., Bergin, E. A., et al. 2019, ApJ, 876, 25

* Bergner, J. B., Öberg, K. I., Guzman, V. V., et al. 2021, ApJS, 257, 11

* Berkowitz, J., Chupka, W., Guyon, P., Holloway, J., & Spohr, R. 1971, J. Chem. Phys., 54, 5165

* Best, T., Otto, R., Trippel, S., et al. 2011, ApJ, 742, 63

* Beth, A., Altwegg, K., Balsiger, H., et al. 2020, A&A, 642, A27

* Bethell, T., & Bergin, E. 2009, Science, 326, 1675

* Blake, G. A., van Dishoeck, E. F., Jansen, D. J., Groesbeck, T. D., & Mundy, L. G. 1994, ApJ, 428, 680

* Bobeldijk, M., van der Zande, W., & Kistemaker, P. 1994, Chem. Phys., 179, 125

* Bodi, A., Hemberger, P., Gerber, T., & Sztaray, B. 2012, Rev. Sci. Instrum., 83, 083105

* Boechat-Roberty, H. M., Pilling, S., & Santos, A. C. F. 2005, A&A, 438, 915

* Booth, A. S., Walsh, C., Terwisscha van Scheltinga, J., et al. 2021, Nat. Astron., 5, 684

* Borsvozszky, J., Nauta, K., Jiang, J., et al. 2021, PNAS, 118, e2113315118

* Bosman, A. D., Alarcon, F., Bergin, E. A., et al. 2021, ApJS, 257, 7

* Bovino, S., Ferrada-Chamorro, S., Lupi, A., Schleicher, D. R. G., & Caselli, P. 2020, MNRAS, 495, L7

* Brown, A., & Balint-Kurti, G. G. 2000a, J. Chem. Phys., 113, 1870

* Brown, A., & Balint-Kurti, G. G. 2000b, J. Chem. Phys., 113, 1879

* Brown, J. M., & Carrington, A. 2003, Rotational Spectroscopy of Diatomic Molecules (Cambridge University Press)

* Bruderer, S., Benz, A. O., Staeuber, P., & Doty, S. D. 2010, ApJ, 720, 1432

* Bruna, P. J., & Hirsch, G. 1987, Mol. Phys., 61, 1359

* Bruna, P., Kammer, W., & Vasudevan, K. 1975, Chem. Phys., 9, 91

* Bruna, P., Buenker, R., & Peyerimhoff, S. 1976, J. Mol. Struct., 32, 217

* Brünken, S., Kluge, L., Stoffels, A., Asvany, O., & Schlemmer, S. 2014, ApJ, 783, L4

* Brunken, N. G. C., Booth, A. S., Leemker, M., et al. 2022, A&A, 659, A29

* Bublitz, J., Kastner, J. H., Hily-Blant, P., et al. 2022, A&A, 659, A197

* Cabezas, C., Agúndez, M., Marcelino, N., et al. 2022, A&A, 657, A4

* Calahan, J. K., Bergin, E. A., & Bosman, A. D. 2022, ApJ, 934, L14

* Carnovale, F., Tseng, R., & Brion, C. 1981, J. Phys. B., 14, 4771

* Caselli, P., & Walmsley, C. M. 2001, ASP Conf. Ser., 243, 67

* Caselli, P., Walmsley, C. M., Terzieva, R., & Herbst, E. 1998, ApJ, 499, 234

* Cashion, J. 1963, J. Chem. Phys., 39, 1872

* Cataldi, G., Wu, Y., Brandeker, A., et al. 2020, ApJ, 892, 99

* Caux, E., Kahane, C., Castets, A., et al. 2011, A&A, 532, A23

* Cazzoletti, P., van Dishoeck, E. F., Visser, R., Facchini, S., & Bruderer, S. 2018, A&A, 609, A93

* Ceccarelli, C., Dominik, C., Lopez-Sepulcre, A., et al. 2014, ApJ, 790, L1

* Cecchi-Pestellini, C., & Aiello, S. 1992, MNRAS, 258, 125

* Cernicharo, J., Heras, A. M., Tielens, A. G. G. M., et al. 2001, ApJ, 546, L123

* Cernicharo, J., Guélin, M., Agúndez, M., et al. 2007, A&A, 467, L37

* Cernicharo, J., Lefloch, B., Agúndez, M., et al. 2018, ApJ, 853, L22

* Cernicharo, J., Agúndez, M., Cabezas, C., et al. 2021a, A&A, 649, L15

* Cernicharo, J., Cabezas, C., Agúndez, M., et al. 2021b, A&A, 648, L3

* Cernicharo, J., Cabezas, C., Endo, Y., et al. 2021c, A&A, 646, L3

* Cernicharo, J., Cabezas, C., Endo, Y., et al. 2021d, A&A, 650, L14

* Chang, Y., Yang, J., Chen, Z., et al. 2020, Chem. Sci., 11, 5089

* Chen, N. L., Gans, B., Hartweg, S., et al. 2022, J. Chem. Phys., 157, 014303

* Chi, X., Jiang, P., Zhu, Q., et al. 2020, ApJ, 891, 16

* Chiang, S. Y., & Lin, I. F. 2005, J. Chem. Phys., 122, 094301

* Chicharro, D. V., Poullain, S. M., Zanchet, A., et al. 2019, Chem. Sci., 10, 6494

* Cleeves, L. I., Adams, F. C., & Bergin, E. A. 2013, ApJ, 772, 5

* Cleeves, L. I., Bergin, E. A., & Adams, F. C. 2014, ApJ, 794, 123

* Cleeves, L. I., Bergin, E. A., Qi, C., Adams, F. C., & Öberg, K. I. 2015, ApJ, 799, 204

* Coates, A. J., Crary, F. J., Lewis, G. R., et al. 2007, Geophys. Res. Lett., 34, L22103

* Codella, C., Lopez-Sepulcre, A., Ohashi, S., et al. 2022, MNRAS, 515, 543

* Continetti, R. E. 2001, Annu. Rev. Phys. Chem., 52, 165
Cool, T. A., Wang, J., Nakajima, K., Taatjes, C. A., & McIlroy, A. 2005, Int. J. Mass Spectr., 247, 18

Cooley, J. W. 1961, Math. Comput., 15, 363

Cooper, G., Burton, G., & Brion, C. 1995, J. Electron. Spectros. Relat. Phenomena, 73, 139

Coppens, P., & Drowart, J. 1995, Chem. Phys. Lett., 243, 108

Cordiner, M. A., Charnley, S. B., Buckle, J. V., Walsh, C., & Millar, T. J. 2011, ApJ, 730, L18

Cordiner, M. A., Buckle, J. V., Wirstrom, E. S., Olofsson, A. O. H., & Charnley, S. B. 2013, ApJ, 770, 48

Cosby, P., & Helm, H. 1988, Chem. Phys. Lett., 152, 71

Coutens, A., Ligterink, N. F. W., Loison, J.-C., et al. 2019, A&A, 623, L13

Cravens, T., & Dalgarno, A. 1978, ApJ, 219, 750

Cravens, T. E., Robertson, I. P., Waite, J. H., et al. 2006, Geophys. Res. Lett., 33, L07105

Cui, G., Zhang, F., & Fang, W. 2010, J. Chem. Phys., 132, 034306

Curdt, W., Brekke, P., Feldman, U., et al. 2001, A&A, 375, 591

Dalgarno, A. 2006a, PNAS, 103, 12269

Dalgarno, A. 2006b, Faraday Discuss., 133, 9

de Oliveira, N., Roudjane, M., Joyeux, D., et al. 2011, Nat. Photon., 5, 149

de Oliveira, N., Joyeux, D., Roudjane, M., et al. 2016, J. Synchrotron Radiat., 23, 887

Decin, L. 2021, ARA&A, 59, 337

Desai, R. T., Coates, A. J., Wellbrock, A., et al. 2017, ApJ, 844, L18

Deyerl, H.-J., Fischer, I., & Chen, P. 1999, J. Chem. Phys., 111, 3441

Dixon, R. N., & Kirby, G. H. 1968, Trans. Faraday Soc., 64, 2002

Dodson, L. G., Shen, L., Savee, J. D., et al. 2015, J. Phys. Chem. A., 119, 1279

Dodson, L. G., Savee, J. D., Gozem, S., et al. 2018, J. Chem. Phys., 148, 184302

Doner, A. C., Moran, H. A., Webb, A. R., et al. 2022, J. Quant. Spectr. Rad. Transf., 108438

Draine, B. 1978, ApJS, 36, 595

Draine, B. T. 2003a, ARA&A, 41, 241

Draine, B. T. 2003b, ApJ, 598, 1017

Draine, B. T. 2003c, ApJ, 598, 1026

Draine, B., & Lee, H. 1984, ApJ, 285, 89

Draine, B. T., & Tan, J. C. 2003, ApJ, 594, 347

Drozdovskaya, M. N., Walsh, C., Visser, R., Harsono, D., & van Dishoeck, E. F. 2014, MNRAS, 445, 913

Drozdovskaya, M. N., van Dishoeck, E. F., Jorgensen, J. K., et al. 2018, MNRAS, 476, 4949

Drummond, B., Tremblin, P., Baraffe, I., et al. 2016, A&A, 594, A69

Drury, C., & Moule, D. 1982, J. Mol. Spectr., 92, 469

Dutrey, A., Guilloteau, S., & Guelin, M. 1997, A&A, 317, L55

Duval, S. E., Bosman, A. D., & Bergin, E. A. 2022, ApJ, 934, L25

Dyke, J. M. 1987, J. Chem. Soc. Faraday Trans., 83, 69

Dyke, J. M. 2019, Phys. Chem. Chem. Phys., 21, 9106

Dyke, J. M., Gamblin, S. D., Haggerston, D., et al. 1998, J. Chem. Phys., 108, 6258

Eddington, A. S. 1928, MNRAS, 88, 352

Eisfeld, W. 2006, J. Phys. Chem. A., 110, 3903

Eland, J. H. D. 1970, Philos. Trans. Roy. Soc. A., 268, 87

Engin, S., Sisourat, N., & Carniato, S. 2012, J. Chem. Phys., 137, 154304

Eppink, A., & Parker, D. H. 1997, Rev. Sci. Instrum., 68, 3477

Fahr, A., Hassanzadeh, P., Laszlo, B., & Huie, R. E. 1997, Chem. Phys., 215, 59

Fahr, A., Hassanzadeh, P., & Atkinson, D. B. 1998, Chem. Phys., 236, 43

Felsmann, D., Moshammer, K., Krueger, J., et al. 2015, Proc. Combust. Inst., 35, 779

Felsmann, D., Lucassen, A., Kruger, J., et al. 2016, Z. Phys. Chem. Intern. J. Res. Phys. Chem., 230, 1067

Feng, R. F., Cooper, G., & Brion, C. E. 2000, Chem. Phys., 260, 391

Feng, R. F., Cooper, G., & Brion, C. E. 2001, Chem. Phys., 270, 319

Fernández-Milán, P., Borràs, V. J., González-Vázquez, J., & Martín, F. 2023, J. Chem. Phys., 158, 134305

France, K., Schindhelm, E., Bergin, E. A., Roueff, E., & Abgrall, H. 2014, ApJ, 784, 127

Frederix, P. W. J. M., Yang, C.-H., Groenenboom, G. C., et al. 2009, J. Phys. Chem. A., 113, 14995

Friedl, R., Brune, W., & Anderson, J. 1983, J. Chem. Phys., 79, 4227

Fu, B., Han, Y., & Bowman, J. M. 2012, Faraday Discuss., 157, 27

Fuente, A., Cernicharo, J., Roueff, E., et al. 2016, A&A, 593, A94

Fuente, A., Goicoechea, J. R., Pety, J., et al. 2017, ApJ, 851, L49

Fuentetaja, R., Agúndez, M., Cabezas, C., et al. 2022, A&A, 667, A4

Fujimoto, M. M., Tanaka, H. K., Marinho, R. R. T., et al. 2020, J. Phys. Chem. A., 124, 6478

Gabici, S. 2022, A&ARV., 30, 4

Gans, B., Mendes, L. A. V., Boye-Peronne, S., et al. 2010, J. Phys. Chem. A., 114, 3237

Gans, B., Boyé-Péronne, S., Broquier, M., et al. 2011a, Phys. Chem. Chem. Phys., 13, 8140

Gans, B., Garcia, G. A., Boyé-Péronne, S., et al. 2011b, J. Phys. Chem. A., 115, 5387

Gans, B., Holzmeier, F., Krüger, J., et al. 2016, J. Chem. Phys., 144, 204307

Gans, B., Garcia, G. A., Holzmeier, F., et al. 2017, J. Chem. Phys., 146, 011101

Gans, B., Garcia, G. A., Boyé-Péronne, S., et al. 2019, Phys. Chem. Chem. Phys., 21, 2337

Gao, H., & Ng, C.-Y. 2019, Chin. J. Chem. Phys., 32, 23

Gao, H., Song, Y., Yang, L., et al. 2011a, J. Chem. Phys., 135, 221101

Gao, H., Yang, L., Pan, Y., et al. 2011b, J. Chem. Phys., 135, 134319

Gao, H., Song, Y., Yang, L., et al. 2012, J. Chem. Phys., 137, 034305

Gao, H., Song, Y., Chang, Y.-C., et al. 2013, J. Phys. Chem. A., 117, 6185

Gao, H., Song, Y., Jackson, W. M., & Ng, C.-Y. 2020, Chin. J. Chem. Phys., 33, 91

Garcia, G. A., Cunha de Miranda, B. K., Tia, M., Daly, S., & Nahon, L. 2013, Rev. Sci. Instrum., 84, 053112-053112-11

Garcia, G. A., Tang, X., Gil, J.-F., et al. 2015, J. Chem. Phys., 142, 164201

Garcia, G. A., Gans, B., Krüger, J., et al. 2018, Phys. Chem. Chem. Phys., 20, 8707

Garcia, G. A., Loison, J.-C., Holzmeier, F., et al. 2021, Mol. Phys., 119, e1825851

Gibson, S. 2016, https://zenodo.org/record/56871

Gibson, S. T., Greene, J. P., & Berkowitz, J. 1985, J. Chem. Phys., 83, 4319

Godard, B., Falgarone, E., Gerin, M., et al. 2012, A&A, 540, A87

Goicoechea, J. R., Rodriguez-Fernandez, N. J., & Cernicharo, J. 2004, ApJ, 600, 214

Goicoechea, J. R., Aguado, A., Cuadrado, S., et al. 2021, A&A, 647, A10

Goldhaber, D. M., & Betz, A. L. 1984, ApJ, 279, L55

González-Vázquez, J., Marante, C., Klinker, M., et al. 2023, XChem_v1, e-cienciaDatos, V3

Gordon, I. E., Rothman, L. S., Hargreaves, R. J., et al. 2022, J. Quant. Spectr. Rad. Transf., 277, 107949

Gredel, R., & Dalgarno, A. 1995, ApJ, 446, 852

Gredel, R., Lepp, S., & Dalgarno, A. 1987, ApJ, 323, L137

Gredel, R., Lepp, S., Dalgarno, A., & Herbst, E. 1989, ApJ, 347, 289

Guardiola, R., & Ros, J. 1982a, J. Comput. Phys., 45, 374

Guardiola, R., & Ros, J. 1982b, J. Comput. Phys., 45, 390

Hachey, M., & Grein, F. 1995a, Can. J. Phys., 73, 18

Hachey, M. & Grein, F. 1995b, Chem. Phys., 197, 61

Haider, S. A., Abdu, M. A., Batista, I. S., et al. 2009, J. Geophys. Res., 114, A03311

Hama, T., & Watanabe, N. 2013, Chem. Rev., 113, 8783

Han, Y.-C., Tsai, P.-Y., Bowman, J. M., & Lin, K.-C. 2017, Phys. Chem. Chem. Phys., 19, 18628

Harada, N., Nishimura, Y., Watanabe, Y., et al. 2019, ApJ, 871, 238

Harper, O. J., Hassenfratz, M., Loison, J. C., et al. 2019, J. Chem. Phys., 150

Harper, O. J., Boyé-Péronne, S., Garcia, G. A., et al. 2020a, J. Chem. Phys., 152, 041105

Harper, O. J., Hassenfratz, M., Loison, J.-C., et al. 2020b, J. Chem. Phys., 152, 189903

Harper, O. J., Gans, B., Loison, J.-C., et al. 2021, J. Phys. Chem. A., 125, 2764

Harper, O. J., Chen, N. L., Boye-Peronne, S., & Gans, B. 2022, Phys. Chem. Chem. Phys., 24, 2777

Harrison, A. W., Kharazmi, A., Shaw, M. F., et al. 2019, Phys. Chem. Phys., 21, 14284

Hartweg, S., Loison, J.-C., Boyé-Péronne, S., et al. 2020, J. Phys. Chem. A., 124, 6050

Hatano, Y. 1999a, Radiat. Environ. Biophys., 38, 239

Hatano, Y. 1999b, Phys. Rep., 313, 110

Hatano, Y. 2001, J. Electron. Spectros. Relat. Phenomena, 119, 107

Heays, A. N., Visser, R., Gredel, R., et al. 2014, A&A, 562, A61

Heays, A. N., Bosman, A. D., & van Dishoeck, E. F. 2017, A&A, 602, A105

Heays, A. N., de Oliveira, N., Gans, B., et al. 2018, J. Quant. Spectr. Rad. Transf., 204, 12

Heazlewood, B. R., Rowling, S. J., Maccarone, A. T., Jordan, M. J. T., & Kable, S. H. 2009, J. Chem. Phys., 130, 054310

Heimann, P. A., Koike, M., Hsu, C. W., et al. 1997, Rev. Sci. Instrum., 68, 1945

Hemberger, P., van Bokhoven, J. A., Perez-Ramirez, J., & Bodi, A. 2020, Catal. Sci. Technol., 10, 1975

Hemberger, P., Bodi, A., Bierkandt, T., et al. 2021, Energy Fuels, 35, 16265

Hemberger, P., Wu, X., Pan, Z., & Bodi, A. 2022, J. Phys. Chem. A., 126, 2196

Herbst, E., Millar, T., Wlodek, S., & Bohme, D. 1989, A&A, 222, 205

Herzberg, G. 1950, Molecular Spectra and Molecular Structure I. Spectra of Diatomic Molecules (Princeton: Van Nostrand)

Hill, C., Yurchenko, S. N., & Tennyson, J. 2013, Icarus, 226, 1673

Hily-Blant, P., Maret, S., Bacmann, A., et al. 2010, A&A, 521, A52
Cool, T. A., Wang, J., Nakajima, K., Taatjes, C. A., & McIlroy, A. 2005, Int. J. Mass Spectr., 247, 18

Cooley, J. W. 1961, Math. Comput., 15, 363

Cooper, G., Burton, G., & Brion, C. 1995, J. Electron. Spectros. Relat. Phenomena, 73, 139

Coppens, P., & Drowart, J. 1995, Chem. Phys. Lett., 243, 108

Cordiner, M. A., Charnley, S. B., Buckle, J. V., Walsh, C., & Millar, T. J. 2011, ApJ, 730, L18

Cordiner, M. A., Buckle, J. V., Wirstrom, E. S., Olofsson, A. O. H., & Charnley, S. B. 2013, ApJ, 770, 48

Cosby, P., & Helm, H. 1988, Chem. Phys. Lett., 152, 71

Coutens, A., Ligterink, N. F. W., Loison, J.-C., et al. 2019, A&A, 623, L13

Cravens, T., & Dalgarno, A. 1978, ApJ, 219, 750

Cravens, T. E., Robertson, I. P., Waite, J. H., et al. 2006, Geophys. Res. Lett., 33, L07105

Cui, G., Zhang, F., & Fang, W. 2010, J. Chem. Phys., 132, 034306

Curdt, W., Brekke, P., Feldman, U., et al. 2001, A&A, 375, 591

Dalgarno, A. 2006a, PNAS, 103, 12269

Dalgarno, A. 2006b, Faraday Discuss., 133, 9

de Oliveira, N., Roudjane, M., Joyeux, D., et al. 2011, Nat. Photon., 5, 149

de Oliveira, N., Joyeux, D., Roudjane, M., et al. 2016, J. Synchrotron Radiat., 23, 887

Decin, L. 2021, ARA&A, 59, 337

Desai, R. T., Coates, A. J., Wellbrock, A., et al. 2017, ApJ, 844, L18

Deyerl, H.-J., Fischer, I., & Chen, P. 1999, J. Chem. Phys., 111, 3441

Dixon, R. N., & Kirby, G. H. 1968, Trans. Faraday Soc., 64, 2002

Dodson, L. G., Shen, L., Savee, J. D., et al. 2015, J. Phys. Chem. A., 119, 1279

Dodson, L. G., Savee, J. D., Gozem, S., et al. 2018, J. Chem. Phys., 148, 184302

Doner, A. C., Moran, H. A., Webb, A. R., et al. 2022, J. Quant. Spectr. Rad. Transf., 108438

Draine, B. 1978, ApJS, 36, 595

Draine, B. T. 2003a, ARA&A, 41, 241

Draine, B. T. 2003b, ApJ, 598, 1017

Draine, B. T. 2003c, ApJ, 598, 1026

Draine, B., & Lee, H. 1984, ApJ, 285, 89

Draine, B. T., & Tan, J. C. 2003, ApJ, 594, 347

Drozdovskaya, M. N., Walsh, C., Visser, R., Harsono, D., & van Dishoeck, E. F. 2014, MNRAS, 445, 913

Drozdovskaya, M. N., van Dishoeck, E. F., Jorgensen, J. K., et al. 2018, MNRAS, 476, 4949

Drummond, B., Tremblin, P., Baraffe, I., et al. 2016, A&A, 594, A69

Drury, C., & Moule, D. 1982, J. Mol. Spectr., 92, 469

Dutrey, A., Guilloteau, S., & Guelin, M. 1997, A&A, 317, L55

Duval, S. E., Bosman, A. D., & Bergin, E. A. 2022, ApJ, 934, L25

Dyke, J. M. 1987, J. Chem. Soc. Faraday Trans., 83, 69

Dyke, J. M. 2019, Phys. Chem. Chem. Phys., 21, 9106

Dyke, J. M., Gamblin, S. D., Haggerston, D., et al. 1998, J. Chem. Phys., 108, 6258

Eddington, A. S. 1928, MNRAS, 88, 352

Eisfeld, W. 2006, J. Phys. Chem. A., 110, 3903

Eland, J. H. D. 1970, Philos. Trans. Roy. Soc. A., 268, 87

Engin, S., Sisourat, N., & Carniato, S. 2012, J. Chem. Phys., 137, 154304

Eppink, A., & Parker, D. H. 1997, Rev. Sci. Instrum., 68, 3477

Fahr, A., Hassanzadeh, P., Laszlo, B., & Huie, R. E. 1997, Chem. Phys., 215, 59

Fahr, A., Hassanzadeh, P., & Atkinson, D. B. 1998, Chem. Phys., 236, 43

Felsmann, D., Moshammer, K., Krueger, J., et al. 2015, Proc. Combust. Inst., 35, 779

Felsmann, D., Lucassen, A., Kruger, J., et al. 2016, Z. Phys. Chem. Intern. J. Res. Phys. Chem., 230, 1067

Feng, R. F., Cooper, G., & Brion, C. E. 2000, Chem. Phys., 260, 391

Feng, R. F., Cooper, G., & Brion, C. E. 2001, Chem. Phys., 270, 319

Fernández-Milán, P., Borràs, V. J., González-Vázquez, J., & Martín, F. 2023, J. Chem. Phys., 158, 134305

France, K., Schindhelm, E., Bergin, E. A., Roueff, E., & Abgrall, H. 2014, ApJ, 784, 127

Frederix, P. W. J. M., Yang, C.-H., Groenenboom, G. C., et al. 2009, J. Phys. Chem. A., 113, 14995

Friedl, R., Brune, W., & Anderson, J. 1983, J. Chem. Phys., 79, 4227

Fu, B., Han, Y., & Bowman, J. M. 2012, Faraday Discuss., 157, 27

Fuente, A., Cernicharo, J., Roueff, E., et al. 2016, A&A, 593, A94

Fuente, A., Goicoechea, J. R., Pety, J., et al. 2017, ApJ, 851, L49

Fuentetaja, R., Agúndez, M., Cabezas, C., et al. 2022, A&A, 667, A4

Fujimoto, M. M., Tanaka, H. K., Marinho, R. R. T., et al. 2020, J. Phys. Chem. A., 124, 6478

Gabici, S. 2022, A&ARV., 30, 4

Gans, B., Mendes, L. A. V., Boye-Peronne, S., et al. 2010, J. Phys. Chem. A., 114, 3237

Gans, B., Boyé-Péronne, S., Broquier, M., et al. 2011a, Phys. Chem. Chem. Phys., 13, 8140

Gans, B., Garcia, G. A., Boyé-Péronne, S., et al. 2011b, J. Phys. Chem. A., 115, 5387

Gans, B., Holzmeier, F., Krüger, J., et al. 2016, J. Chem. Phys., 144, 204307

Gans, B., Garcia, G. A., Holzmeier, F., et al. 2017, J. Chem. Phys., 146, 011101

Gans, B., Garcia, G. A., Boyé-Péronne, S., et al. 2019, Phys. Chem. Chem. Phys., 21, 2337

Gao, H., & Ng, C.-Y. 2019, Chin. J. Chem. Phys., 32, 23

Gao, H., Song, Y., Yang, L., et al. 2011a, J. Chem. Phys., 135, 221101

Gao, H., Yang, L., Pan, Y., et al. 2011b, J. Chem. Phys., 135, 134319

Gao, H., Song, Y., Yang, L., et al. 2012, J. Chem. Phys., 137, 034305

Gao, H., Song, Y., Chang, Y.-C., et al. 2013, J. Phys. Chem. A., 117, 6185

Gao, H., Song, Y., Jackson, W. M., & Ng, C.-Y. 2020, Chin. J. Chem. Phys., 33, 91

Garcia, G. A., Cunha de Miranda, B. K., Tia, M., Daly, S., & Nahon, L. 2013, Rev. Sci. Instrum., 84, 053112-053112-11

Garcia, G. A., Tang, X., Gil, J.-F., et al. 2015, J. Chem. Phys., 142, 164201

Garcia, G. A., Gans, B., Krüger, J., et al. 2018, Phys. Chem. Chem. Phys., 20, 8707

Garcia, G. A., Loison, J.-C., Holzmeier, F., et al. 2021, Mol. Phys., 119, e1825851

Gibson, S. 2016, https://zenodo.org/record/56871

Gibson, S. T., Greene, J. P., & Berkowitz, J. 1985, J. Chem. Phys., 83, 4319

Godard, B., Falgarone, E., Gerin, M., et al. 2012, A&A, 540, A87

Goicoechea, J. R., Rodriguez-Fernandez, N. J., & Cernicharo, J. 2004, ApJ, 600, 214

Goicoechea, J. R., Aguado, A., Cuadrado, S., et al. 2021, A&A, 647, A10

Goldhaber, D. M., & Betz, A. L. 1984, ApJ, 279, L55

González-Vázquez, J., Marante, C., Klinker, M., et al. 2023, XChem_v1, e-cienciaDatos, V3

Gordon, I. E., Rothman, L. S., Hargreaves, R. J., et al. 2022, J. Quant. Spectr. Rad. Transf., 277, 107949

Gredel, R., & Dalgarno, A. 1995, ApJ, 446, 852

Gredel, R., Lepp, S., & Dalgarno, A. 1987, ApJ, 323, L137

Gredel, R., Lepp, S., Dalgarno, A., & Herbst, E. 1989, ApJ, 347, 289

Guardiola, R., & Ros, J. 1982a, J. Comput. Phys., 45, 374

Guardiola, R., & Ros, J. 1982b, J. Comput. Phys., 45, 390

Hachey, M., & Grein, F. 1995a, Can. J. Phys., 73, 18

Hachey, M. & Grein, F. 1995b, Chem. Phys., 197, 61

Haider, S. A., Abdu, M. A., Batista, I. S., et al. 2009, J. Geophys. Res., 114, A03311

Hama, T., & Watanabe, N. 2013, Chem. Rev., 113, 8783

Han, Y.-C., Tsai, P.-Y., Bowman, J. M., & Lin, K.-C. 2017, Phys. Chem. Chem. Phys., 19, 18628

Harada, N., Nishimura, Y., Watanabe, Y., et al. 2019, ApJ, 871, 238

Harper, O. J., Hassenfratz, M., Loison, J. C., et al. 2019, J. Chem. Phys., 150

Harper, O. J., Boyé-Péronne, S., Garcia, G. A., et al. 2020a, J. Chem. Phys., 152, 041105

Harper, O. J., Hassenfratz, M., Loison, J.-C., et al. 2020b, J. Chem. Phys., 152, 189903

Harper, O. J., Gans, B., Loison, J.-C., et al. 2021, J. Phys. Chem. A., 125, 2764

Harper, O. J., Chen, N. L., Boye-Peronne, S., & Gans, B. 2022, Phys. Chem. Chem. Phys., 24, 2777

Harrison, A. W., Kharazmi, A., Shaw, M. F., et al. 2019, Phys. Chem. Phys., 21, 14284

Hartweg, S., Loison, J.-C., Boyé-Péronne, S., et al. 2020, J. Phys. Chem. A., 124, 6050

Hatano, Y. 1999a, Radiat. Environ. Biophys., 38, 239

Hatano, Y. 1999b, Phys. Rep., 313, 110

Hatano, Y. 2001, J. Electron. Spectros. Relat. Phenomena, 119, 107

Heays, A. N., Visser, R., Gredel, R., et al. 2014, A&A, 562, A61

Heays, A. N., Bosman, A. D., & van Dishoeck, E. F. 2017, A&A, 602, A105

Heays, A. N., de Oliveira, N., Gans, B., et al. 2018, J. Quant. Spectr. Rad. Transf., 204, 12

Heazlewood, B. R., Rowling, S. J., Maccarone, A. T., Jordan, M. J. T., & Kable, S. H. 2009, J. Chem. Phys., 130, 054310

Heimann, P. A., Koike, M., Hsu, C. W., et al. 1997, Rev. Sci. Instrum., 68, 1945

Hemberger, P., van Bokhoven, J. A., Perez-Ramirez, J., & Bodi, A. 2020, Catal. Sci. Technol., 10, 1975

Hemberger, P., Bodi, A., Bierkandt, T., et al. 2021, Energy Fuels, 35, 16265

Hemberger, P., Wu, X., Pan, Z., & Bodi, A. 2022, J. Phys. Chem. A., 126, 2196

Herbst, E., Millar, T., Wlodek, S., & Bohme, D. 1989, A&A, 222, 205

Herzberg, G. 1950, Molecular Spectra and Molecular Structure I. Spectra of Diatomic Molecules (Princeton: Van Nostrand)

Hill, C., Yurchenko, S. N., & Tennyson, J. 2013, Icarus, 226, 1673

Hily-Blant, P., Maret, S., Bacmann, A., et al. 2010, A&A, 521, A52
Hitchcock, A., Williams, G., Brion, C., & Langhoff, P. 1984, *Chem. Phys.*, **88**, 65

Hochlaf, M. 2017, *Phys. Chem. Chem. Phys.*, **19**, 21236

Holzmeier, F., Lang, M., Fischer, I., et al. 2015, *J. Chem. Phys.*, **142**, 184306

Holzmeier, F., Fischer, I., Kiendl, B., et al. 2016, *Phys. Chem. Chem. Phys.*, **18**, 9240

Hrodmarsson, H. R., Garcia, G. A., Nahon, L., Loison, J.-C., & Gans, B. 2019a, *Phys. Chem. Chem. Phys.*, **21**, 25907

Hrodmarsson, H. R., Garcia, G. A., Nahon, L., Loison, J.-C., & Gans, B. 2019b, *J. Phys. Chem. A*, **123**, 9193

Hrodmarsson, H. R., Garcia, G. A., Nahon, L., Loison, J.-C., & Gans, B. 2021, *J. Mol. Spectr.*, **381**, 111533

Huang, C., Yang, B., Zhang, F., & Tian, G. 2018, *Combust. Flame*, **198**, 334

Hung, K.-C., Tsai, P.-Y., Li, H.-K., & Lin, K.-C. 2014, *J. Chem. Phys.*, **140**, 064313

Hunziker, H., Kneppe, H., McLean, A., Siegbahn, P., & Wendt, H. 1983, *Can. J. Chem.*, **61**, 993

Hurzeler, H., Inghram, M., & Morrison, J. 1958, *J. Chem. Phys.*, **28**, 76

Indriolo, N. 2012, *Philos. Trans. Roy. Soc. A.*, **370**, 5142

Indriolo, N., & McCall, B. J. 2012, *ApJ*, **745**, 91

Indriolo, N., Neufeld, D. A., DeWitt, C. N., et al. 2015, *ApJ*, **802**, L14

Ivlev, A. V., Silsbee, K., Sipilae, O., & Caselli, P. 2019, *ApJ*, **884**, 176

Jacovella, U., Gans, B., & Merkt, F. 2013, *J. Chem. Phys.*, **139**, 084308

Jessup, K. L., Spencer, J., & Yelle, R. 2007, *Icarus*, **192**, 24

Jin, M., Lee, J.-E., & Kim, K.-T. 2015, *ApJS*, **219**, 2

Johns, J., & Ramsay, D. 1961, *Can. J. Phys.*, **39**, 210

Johnson, B. 1978, *J. Chem. Phys.*, **69**, 4678

Johnson, M., Bodi, A., Schulz, L., & Gerber, T. 2009, *Nucl. Instrum. Methods. Phys. Res. A.*, **610**, 597

Jolly, G. S., Singleton, D. L., & Paraskevopoulos, G. 1987, *J. Phys. Chem.*, **91**, 3463

Kameta, K., Ukai, M., Kamosaki, T., et al. 1992, *J. Chem. Phys.*, **96**, 4911

Kameta, K., Machida, S., Kitajima, M., et al. 1996, *J. Electron. Spectros. Relat. Phenomena*, **79**, 391

Kameta, K., Ukai, M., Chiba, R., et al. 1998, *J. Chem. Phys.*, **95**, 1456

Kameta, K., Kouchi, N., Ukai, M., & Hatano, Y. 2002, *J. Electron. Spectros. Relat. Phenomena*, **123**, 225

Kawashima, Y., & Ikoma, M. 2019, *ApJ*, **877**, 109

Keller-Rudek, H., Moortgat, G. K., Sander, R., & Sörensen, R. 2013, *Earth Syst. Sci. Data*, **5**, 365

Kim, S. J., AH'earn, M. F., Wellnitz, D. D., Meier, R., & Lee, Y. S. 2003, *Icarus*, **166**, 157

Kirby, K. P., & Van Dishoeck, E. F. 1989, in *Advances in Atomic and Molecular Physics*, eds. D. Bates, & B. Bederson (Elsevier), 25, 437

Knutson, H. A., Howard, A. W., & Isaacson, H. 2010, *ApJ*, **720**, 1569

Koch, A. 1997, *J. Phys. Chem. A.*, **101**, 1460

Kral, Q., Matra, L., Wyatt, M. C., & Kennedy, G. M. 2017, *MNRAS*, **469**, 521

Kral, Q., Marino, S., Wyatt, M. C., Kama, M., & Matra, L. 2019, *MNRAS*, **489**, 3670

Kroto, H., & Suffolk, R. 1972, *Chem. Phys. Lett.*, **15**, 545

Krueger, J., Garcia, G. A., Felsmann, D., et al. 2014, *Phys. Chem. Chem. Phys.*, **16**, 22791

Kulander, K. C., & Heller, E. J. 1978, *J. Chem. Phys.*, **69**, 2439

Kumar, S. S., Hauser, D., Jindra, R., et al. 2013, *ApJ*, **776**, 25

Langford, S. R., Batten, A. D., Kono, M., & Ashfold, M. N. R. 1997, *J. Chem. Soc. Faraday Trans.*, **93**, 3757

Langhoff, S. R., & Jaffe, R. L. 1979, *J. Chem. Phys.*, **71**, 1475

Larsson, B., Liseau, R., Pagani, L., et al. 2007, *A&A*, **466**, 999

Larsson, M., Geppert, W. D., & Nyman, G. 2012, *Rep. Prog. Phys.*, **75**, 066901

Latif, M. A., & Khochfar, S. 2019, *MNRAS*, **490**, 2706

Leach, S., Schwell, M., Dulieu, F., et al. 2002, *Phys. Chem. Chem. Phys.*, **4**, 5025

Lee, S., & Sun, H. S. 2001, *Bull. Korean Chem. Soc.*, **22**, 210

Lee, S., Sun, H., Kim, B., & Freed, K. F. 2001, *J. Chem. Phys.*, **114**, 5537

Lee, K. L. K., Quinn, M. S., Maccarone, A. T., et al. 2014, *Chem. Sci.*, **5**, 4633

Lefebvre-Brion, H., & Field, R. W. 1986, *Perturbations in the Spectra of Diatomic Molecules* (Academic Press)

Lefebvre-Brion, H., & Field, R. W. 2004, *The Spectra and Dynamics of Diatomic Molecules* (Academic Press)

Le Gal, R., Oberg, K., Loomis, R. A., Pegues, J., & Bergner, J. B. 2019, *ApJ*, **876**, 72

Le Roy, R. J. 2017, *J. Quant. Spectr. Rad. Transf.*, **186**, 167

Lewerenz, M., Bruna, P., Peyerimhoff, S., & Buenker, R. 1983a, *J. Phys. B.*, **16**, 4511

Lewerenz, M., Bruna, P., Peyerimhoff, S., & Buenker, R. 1983b, *Mol. Phys.*, **49**, 1

Lewis, B. R., Gibson, S. T., Stark, G., & Heays, A. N. 2018, *J. Chem. Phys.*, **148**, 244303

Li, A., & Draine, B. T. 2001, *ApJ*, **550**, L213

Li, X., Heays, A. N., Visser, R., et al. 2013, *A&A*, **555**, A14

Li, H.-K., Tsai, P.-Y., Hung, K.-C., Kasai, T., & Lin, K.-C. 2015, *J. Chem. Phys.*, **142**, 041101

Li, X., Millar, T. J., Heays, A. N., et al. 2016, *A&A*, **588**, A4

Liao, C. L., & Ng, C. Y. 1986, *J. Chem. Phys.*, **84**, 778

Limão-Vieira, P., Eden, S., Mason, N., & Hoffmann, S. 2003, *Chem. Phys. Lett.*, **376**, 737

Long, F., Bosman, A. D., Cazzoletti, P., et al. 2021, *A&A*, **647**, A118

Loomis, R. A., Burkhardt, A. M., Shingledecker, C. N., et al. 2021, *Nat. Astron.*, **5**, 188

Lu, Z., Chang, Y. C., Gao, H., et al. 2014, *J. Chem. Phys.*, **140**, 231101

Luo, Y., Shlosman, I., Nagamine, K., & Fang, T. 2020, *MNRAS*, **492**, 4917

Madhusudhan, N. 2019, *ARA&A*, **57**, 617

Madhusudhan, N., Agúndez, M., Moses, J. I., & Hu, Y. 2016, *Space Sci. Rev.*, **205**, 285

Majumdar, L., Gratier, P., Vidal, T., et al. 2016, *MNRAS*, **458**, 1859

Marante, C., Argenti, L., & Martin, F. 2014, *Phys. Rev. A*, **90**, 012506

Marante, C., Klinker, M., Corral, I., et al. 2017a, *J. Chem. Theory Comput.*, **13**, 499

Marante, C., Klinker, M., Kjellsson, T., et al. 2017b, *Phys. Rev. A*, **96**, 022507

Maret, S., & Bergin, E. A. 2007, *ApJ*, **664**, 956

Marggi Poullain, S., Chicharro, D. V., Zanchet, A., et al. 2019, *Phys. Chem. Chem. Phys.*, **21**, 23017

Martín-Doménech, R., Jiménez-Serra, I., Muñoz Caro, G. M., et al. 2016, *A&A*, **585**, A112

Martinez, R., Buitrago, A., Howell, N., Hearn, C., & Joens, J. 1992, *Atmos. Environ.* A. Gen. Top., **26**, 785

Mathis, J., Mezger, P., & Panagia, N. 1983, *A&A*, **128**, 212

McAdam, K., Veyret, B., & Lesclaux, R. 1987, *Chem. Phys. Lett.*, **133**, 39

McCarthy, M. C., Gottlieb, C. A., Gupta, H., & Thaddeus, P. 2006, *ApJ*, **652**, L141

McGuire, B. A. 2022, *ApJS*, **259**, 30

McGuire, B. A., Burkhardt, A. M., Loomis, R. A., et al. 2020, *ApJ*, **900**, L10

Menten, K. M., Wyrowski, F., Belloche, A., et al. 2011, *A&A*, **525**, A77

Mercier, X., Faccinetto, A., Batut, S., et al. 2020, *Phys. Chem. Chem. Phys.*, **22**, 15926

Merrill, P. 1955, *PASP*, **67**, 199

Millar, T. J., Walsh, C., Cordiner, M. A., Ní Chuimín, R., & Herbst, E. 2007, *ApJ*, **662**, L87

Millar, T. J., Walsh, C., & Field, T. A. 2017, *Chem. Rev.*, **117**, 1765

Miotello, A., Facchini, S., van Dishoeck, E. F., & Bruderer, S. 2018, *A&A*, **619**, A113

Mitsuke, K., Hattori, H., & Yoshida, H. 1993a, *J. Chem. Phys.*, **99**, 6642

Mitsuke, K., Yoshida, H., & Hattori, H. 1993b, *Z. Phys. D.*, **27**, 267

Mizus, I. I., Polyansky, O. L., McKemmish, L. K., et al. 2019, *Mol. Phys.*, **117**, 1663

Moor, A., Kral, Q., Abraham, P., et al. 2019, *ApJ*, **884**, 108

Morajkar, P., Bossolasco, A., Schoemaecker, C., & Fittschen, C. 2014, *J. Chem. Phys.*, **140**, 214308

Mukundan, V., & Bhardwaj, A. 2018, *ApJ*, **856**, 168

Munk, J., Pagsberg, P., Ratajczak, E., & Sillesen, A. 1986, *J. Phys. Chem.*, **90**, 2752

Murillo, N. M., van Dishoeck, E. F., van der Wiel, M. H. D., et al. 2018, *A&A*, **617**, A120

Nahon, L., de Oliveira, N., Garcia, G. A., et al. 2012, *J. Synchrotron Radiat.*, **19**, 508

Nee, J., Suto, M., & Lee, L. 1985, *J. Phys. B.*, **18**, L293

Neufeld, D. A., & Wolfire, M. G. 2009, *ApJ*, **706**, 1594

Neufeld, D. A., & Wolfire, M. G. 2016, *ApJ*, **826**, 183

Neufeld, D. A., Falgarone, E., Gerin, M., et al. 2012, *A&A*, **542**, A6

Neufeld, D. A., Godard, B., Gerin, M., et al. 2015, *A&A*, **577**, A49

Nguyen, T. L., Mebel, A. M., & Kaiser, R. I. 2001a, *J. Phys. Chem. A.*, **105**, 3284

Nguyen, T. L., Mebel, A. M., Lin, S. H., & Kaiser, R. I. 2001b, *J. Phys. Chem. A.*, **105**, 11549

Nickerson, S., Teyssier, R., & Rosdahl, J. 2018, *MNRAS*, **479**, 3206

Noll, K., Mcgrath, M., Trafton, L., et al. 1995, *Science*, **267**, 1307

Norwood, K., Nourbakhsh, S., He, G., & Ng, C. 1991, *Chem. Phys. Lett.*, **184**, 147

Notsu, S., van Dishoeck, E. F., Walsh, C., Bosman, A. D., & Nomura, H. 2021, *A&A*, **650**, A180

Noumerov, B. V. 1924, *MNRAS*, **84**, 592

Nunes, Y., Martins, G., Mason, N. J., et al. 2010, *Phys. Chem. Chem. Phys.*, **12**, 15734
Hitchcock, A., Williams, G., Brion, C., & Langhoff, P. 1984, Chem. Phys., 88, 65

Hochlaf, M. 2017, Phys. Chem. Chem. Phys., 19, 21236

Holzmeier, F., Lang, M., Fischer, I., et al. 2015, J. Chem. Phys., 142, 184306

Holzmeier, F., Fischer, I., Kiendl, B., et al. 2016, Phys. Chem. Chem. Phys., 18, 9240

Hrodmarsson, H. R., Garcia, G. A., Nahon, L., Loison, J.-C., & Gans, B. 2019a, Phys. Chem. Chem. Phys., 21, 25907

Hrodmarsson, H. R., Garcia, G. A., Nahon, L., Loison, J.-C., & Gans, B. 2019b, J. Phys. Chem. A, 123, 9193

Hrodmarsson, H. R., Garcia, G. A., Nahon, L., Loison, J.-C., & Gans, B. 2021, J. Mol. Spectr., 381, 111533

Huang, C., Yang, B., Zhang, F., & Tian, G. 2018, Combust. Flame, 198, 334

Hung, K.-C., Tsai, P.-Y., Li, H.-K., & Lin, K.-C. 2014, J. Chem. Phys., 140, 064313

Hunziker, H., Kneppe, H., McLean, A., Siegbahn, P., & Wendt, H. 1983, Can. J. Chem., 61, 993

Hurzeler, H., Inghram, M., & Morrison, J. 1958, J. Chem. Phys., 28, 76

Indriolo, N. 2012, Philos. Trans. Roy. Soc. A., 370, 5142

Indriolo, N., & McCall, B. J. 2012, ApJ, 745, 91

Indriolo, N., Neufeld, D. A., DeWitt, C. N., et al. 2015, ApJ, 802, L14

Ivlev, A. V., Silsbee, K., Sipilae, O., & Caselli, P. 2019, ApJ, 884, 176

Jacovella, U., Gans, B., & Merkt, F. 2013, J. Chem. Phys., 139, 084308

Jessup, K. L., Spencer, J., & Yelle, R. 2007, Icarus, 192, 24

Jin, M., Lee, J.-E., & Kim, K.-T. 2015, ApJS, 219, 2

Johns, J., & Ramsay, D. 1961, Can. J. Phys., 39, 210

Johnson, B. 1978, J. Chem. Phys., 69, 4678

Johnson, M., Bodi, A., Schulz, L., & Gerber, T. 2009, Nucl. Instrum. Methods. Phys. Res. A., 610, 597

Jolly, G. S., Singleton, D. L., & Paraskevopoulos, G. 1987, J. Phys. Chem., 91, 3463

Kameta, K., Ukai, M., Kamosaki, T., et al. 1992, J. Chem. Phys., 96, 4911

Kameta, K., Machida, S., Kitajima, M., et al. 1996, J. Electron. Spectros. Relat. Phenomena, 79, 391

Kameta, K., Ukai, M., Chiba, R., et al. 1998, J. Chem. Phys., 95, 1456

Kameta, K., Kouchi, N., Ukai, M., & Hatano, Y. 2002, J. Electron. Spectros. Relat. Phenomena, 123, 225

Kawashima, Y., & Ikoma, M. 2019, ApJ, 877, 109

Keller-Rudek, H., Moortgat, G. K., Sander, R., & Sörensen, R. 2013, Earth Syst. Sci. Data, 5, 365

Kim, S. J., AH'earn, M. F., Wellnitz, D. D., Meier, R., & Lee, Y. S. 2003, Icarus, 166, 157

Kirby, K. P., & Van Dishoeck, E. F. 1989, in Advances in Atomic and Molecular Physics, eds. D. Bates, & B. Bederson (Elsevier), 25, 437

Knutson, H. A., Howard, A. W., & Isaacson, H. 2010, ApJ, 720, 1569

Koch, A. 1997, J. Phys. Chem. A., 101, 1460

Kral, Q., Matra, L., Wyatt, M. C., & Kennedy, G. M. 2017, MNRAS, 469, 521

Kral, Q., Marino, S., Wyatt, M. C., Kama, M., & Matra, L. 2019, MNRAS, 489, 3670

Kroto, H., & Suffolk, R. 1972, Chem. Phys. Lett., 15, 545

Krueger, J., Garcia, G. A., Felsmann, D., et al. 2014, Phys. Chem. Chem. Phys., 16, 22791

Kulander, K. C., & Heller, E. J. 1978, J. Chem. Phys., 69, 2439

Kumar, S. S., Hauser, D., Jindra, R., et al. 2013, ApJ, 776, 25

Langford, S. R., Batten, A. D., Kono, M., & Ashfold, M. N. R. 1997, J. Chem. Soc. Faraday Trans., 93, 3757

Langhoff, S. R., & Jaffe, R. L. 1979, J. Chem. Phys., 71, 1475

Larsson, B., Liseau, R., Pagani, L., et al. 2007, A&A, 466, 999

Larsson, M., Geppert, W. D., & Nyman, G. 2012, Rep. Prog. Phys., 75, 066901

Latif, M. A., & Khochfar, S. 2019, MNRAS, 490, 2706

Leach, S., Schwell, M., Dulieu, F., et al. 2002, Phys. Chem. Chem. Phys., 4, 5025

Lee, S., & Sun, H. S. 2001, Bull. Korean Chem. Soc., 22, 210

Lee, S., Sun, H., Kim, B., & Freed, K. F. 2001, J. Chem. Phys., 114, 5537

Lee, K. L. K., Quinn, M. S., Maccarone, A. T., et al. 2014, Chem. Sci., 5, 4633

Lefebvre-Brion, H., & Field, R. W. 1986, Perturbations in the Spectra of Diatomic Molecules (Academic Press)

Lefebvre-Brion, H., & Field, R. W. 2004, The Spectra and Dynamics of Diatomic Molecules (Academic Press)

Le Gal, R., Oberg, K., Loomis, R. A., Pegues, J., & Bergner, J. B. 2019, ApJ, 876, 72

Le Roy, R. J. 2017, J. Quant. Spectr. Rad. Transf., 186, 167

Lewerenz, M., Bruna, P., Peyerimhoff, S., & Buenker, R. 1983a, J. Phys. B., 16, 4511

Lewerenz, M., Bruna, P., Peyerimhoff, S., & Buenker, R. 1983b, Mol. Phys., 49, 1

Lewis, B. R., Gibson, S. T., Stark, G., & Heays, A. N. 2018, J. Chem. Phys., 148, 244303

Li, A., & Draine, B. T. 2001, ApJ, 550, L213

Li, X., Heays, A. N., Visser, R., et al. 2013, A&A, 555, A14

Li, H.-K., Tsai, P.-Y., Hung, K.-C., Kasai, T., & Lin, K.-C. 2015, J. Chem. Phys., 142, 041101

Li, X., Millar, T. J., Heays, A. N., et al. 2016, A&A, 588, A4

Liao, C. L., & Ng, C. Y. 1986, J. Chem. Phys., 84, 778

Limão-Vieira, P., Eden, S., Mason, N., & Hoffmann, S. 2003, Chem. Phys. Lett., 376, 737

Long, F., Bosman, A. D., Cazzoletti, P., et al. 2021, A&A, 647, A118

Loomis, R. A., Burkhardt, A. M., Shingledecker, C. N., et al. 2021, Nat. Astron., 5, 188

Lu, Z., Chang, Y. C., Gao, H., et al. 2014, J. Chem. Phys., 140, 231101

Luo, Y., Shlosman, I., Nagamine, K., & Fang, T. 2020, MNRAS, 492, 4917

Madhusudhan, N. 2019, ARA&A, 57, 617

Madhusudhan, N., Agúndez, M., Moses, J. I., & Hu, Y. 2016, Space Sci. Rev., 205, 285

Majumdar, L., Gratier, P., Vidal, T., et al. 2016, MNRAS, 458, 1859

Marante, C., Argenti, L., & Martin, F. 2014, Phys. Rev. A., 90, 012506

Marante, C., Klinker, M., Corral, I., et al. 2017a, J. Chem. Theory Comput., 13, 499

Marante, C., Klinker, M., Kjellsson, T., et al. 2017b, Phys. Rev. A., 96, 022507

Maret, S., & Bergin, E. A. 2007, ApJ, 664, 956

Marggi Poullain, S., Chicharro, D. V., Zanchet, A., et al. 2019, Phys. Chem. Chem. Phys., 21, 23017

Martín-Doménech, R., Jiménez-Serra, I., Muñoz Caro, G. M., et al. 2016, A&A, 585, A112

Martinez, R., Buitrago, A., Howell, N., Hearn, C., & Joens, J. 1992, Atmos. Environ. A. Gen. Top., 26, 785

Mathis, J., Mezger, P., & Panagia, N. 1983, A&A, 128, 212

McAdam, K., Veyret, B., & Lesclaux, R. 1987, Chem. Phys. Lett., 133, 39

McCarthy, M. C., Gottlieb, C. A., Gupta, H., & Thaddeus, P. 2006, ApJ, 652, L141

McGuire, B. A. 2022, ApJS, 259, 30

McGuire, B. A., Burkhardt, A. M., Loomis, R. A., et al. 2020, ApJ, 900, L10

Menten, K. M., Wyrowski, F., Belloche, A., et al. 2011, A&A, 525, A77

Mercier, X., Faccinetto, A., Batut, S., et al. 2020, Phys. Chem. Chem. Phys., 22, 15926

Merrill, P. 1955, PASP, 67, 199

Millar, T. J., Walsh, C., Cordiner, M. A., Ní Chuimín, R., & Herbst, E. 2007, ApJ, 662, L87

Millar, T. J., Walsh, C., & Field, T. A. 2017, Chem. Rev., 117, 1765

Miotello, A., Facchini, S., van Dishoeck, E. F., & Bruderer, S. 2018, A&A, 619, A113

Mitsuke, K., Hattori, H., & Yoshida, H. 1993a, J. Chem. Phys., 99, 6642

Mitsuke, K., Yoshida, H., & Hattori, H. 1993b, Z. Phys. D., 27, 267

Mizus, I. I., Polyansky, O. L., McKemmish, L. K., et al. 2019, Mol. Phys., 117, 1663

Moor, A., Kral, Q., Abraham, P., et al. 2019, ApJ, 884, 108

Morajkar, P., Bossolasco, A., Schoemaecker, C., & Fittschen, C. 2014, J. Chem. Phys., 140, 214308

Mukundan, V., & Bhardwaj, A. 2018, ApJ, 856, 168

Munk, J., Pagsberg, P., Ratajczak, E., & Sillesen, A. 1986, J. Phys. Chem., 90, 2752

Murillo, N. M., van Dishoeck, E. F., van der Wiel, M. H. D., et al. 2018, A&A, 617, A120

Nahon, L., de Oliveira, N., Garcia, G. A., et al. 2012, J. Synchrotron Radiat., 19, 508

Nee, J., Suto, M., & Lee, L. 1985, J. Phys. B., 18, L293

Neufeld, D. A., & Wolfire, M. G. 2009, ApJ, 706, 1594

Neufeld, D. A., & Wolfire, M. G. 2016, ApJ, 826, 183

Neufeld, D. A., Falgarone, E., Gerin, M., et al. 2012, A&A, 542, A6

Neufeld, D. A., Godard, B., Gerin, M., et al. 2015, A&A, 577, A49

Nguyen, T. L., Mebel, A. M., & Kaiser, R. I. 2001a, J. Phys. Chem. A., 105, 3284

Nguyen, T. L., Mebel, A. M., Lin, S. H., & Kaiser, R. I. 2001b, J. Phys. Chem. A., 105, 11549

Nickerson, S., Teyssier, R., & Rosdahl, J. 2018, MNRAS, 479, 3206

Noll, K., Mcgrath, M., Trafton, L., et al. 1995, Science, 267, 1307

Norwood, K., Nourbakhsh, S., He, G., & Ng, C. 1991, Chem. Phys. Lett., 184, 147

Notsu, S., van Dishoeck, E. F., Walsh, C., Bosman, A. D., & Nomura, H. 2021, A&A, 650, A180

Noumerov, B. V. 1924, MNRAS, 84, 592

Nunes, Y., Martins, G., Mason, N. J., et al. 2010, Phys. Chem. Chem. Phys., 12, 15734
Öberg, K. I., & Bergin, E. A. 2021, Phys. Rep., 893, 1

Okabe, H. 1970, J. Chem. Phys., 53, 3507

Osborn, D. L., Zou, P., Johnsen, H., et al. 2008, Rev. Sci. Instrum., 79, 104103

Osted, A., Kongsted, J., & Christiansen, O. 2005, J. Phys. Chem. A., 109, 1430

Padial, N., Collins, L., & Schneider, B. 1985, ApJ, 298, 369

Padovani, M., & Galli, D. 2011, A&A, 530, A109

Padovani, M., Galli, D., & Glassgold, A. E. 2009, A&A, 501, 619

Padovani, M., Hennebelle, P., & Galli, D. 2013, A&A, 560, A114

Padovani, M., Marcowith, A., Hennebelle, P., & Ferrière, K. 2016, A&A, 590, A8

Padovani, M., Galli, D., Ivlev, A., Caselli, P., & Ferrara, A. 2018a, A&A, 619, A144

Padovani, M., Ivlev, A. V., Galli, D., & Caselli, P. 2018b, A&A, 614, A111

Padovani, M., Ivlev, A. V., Galli, D., et al. 2020, Space Sci. Rev., 216, 29

Pan, Z., Bodi, A., Bokhoven, v. J. A., & Hemberger, P. 2022, Phys. Chem. Chem. Phys., 24, 3655

Parise, B., Bergman, P., & Du, F. 2012, A&A, 541, A11

Petrignani, A., Bing, D., Novotny, O., et al. 2010, J. Phys. Chem. A., 114, 4864

Pety, J., Gratier, P., Guzmán, V., et al. 2012, A&A, 548, A68

Pezzella, M., Yurchenko, S. N., & Tennyson, J. 2021, Phys. Chem. Chem. Phys., 23, 16390

Pezzella, M., Tennyson, J., & Yurchenko, S. N. 2022, MNRAS, 514, 4413

Phan, V. H. M., Morlino, G., & Gabici, S. 2018, MNRAS, 480, 5167

Phan, V. H. M., Schulze, F., Mertsch, P., Recchia, S., & Gabici, S. 2021, Phys. Rev. Lett., 127, 141101

Phuong, N. T., Chapillon, E., Majumdar, L., et al. 2018, A&A, 616, A5

Pieper, J., Schmitt, S., Hemken, C., et al. 2018, Z. Phys. Chem. Intern. J. Res. Phys. Chem., 232, 153

Platzman, R. 1962, Radiat. Res., 16, 419

Podio, L., Lefloch, B., Ceccarelli, C., Codella, C., & Bachiller, R. 2014, A&A, 565, A64

Ponzi, A., Angeli, C., Cimiraglia, R., Coriani, S., & Decleva, P. 2014, J. Chem. Phys., 140, 204304

Pouilly, B., Robbe, J., Schamps, J., & Roueff, E. 1983, J. Phys. B., 16, 437

Pouilly, J. C., Schermann, J. P., Nieuwjaer, N., et al. 2010, Phys. Chem. Chem. Phys., 12, 3566

Pradhan, A. D., & Partridge, H. 1996, Chem. Phys. Lett., 255, 163

Prasad, S., & Tarafdar, S. 1983, ApJ, 267, 603

Qi, C., Öberg, K. I., Wilner, D. J., & Rosenfeld, K. A. 2013, ApJ, 765, L14

Qin, Z., Bai, T., & Liu, L. 2022, MNRAS, 516, 550

Qu, Q., Yurchenko, S. N., & Tennyson, J. 2022, J. Chem. Theory Comput., 18, 1808

Recchia, S., Phan, V. H. M., Biswas, S., & Gabici, S. 2019, MNRAS, 485, 2276

Resende, S. M., & Ornellas, F. R. 2001, J. Chem. Phys., 115, 2178

Reusch, E., Holzmeier, F., Constantinidis, P., Hemberger, P., & Fischer, I. 2017, Angew. Chem. Int. Ed., 56, 8000

Riaz, B., Thi, W.-F., & Caselli, P. 2019, MNRAS, 483, 1139

Rizzo, J. R., Guente, A., & Garcia-Burlo, S. 2005, ASP Conf. Ser., 344, 184

Roberge, W. G., Jones, D., Lepp, S., & Dalgarno, A. 1991, ApJS, 77, 287

Robertson, I. P., Cravens, T. E., Waite, J. H., et al. 2009, Planet. Space Sci., 57, 1834

Robinson, J. C., Sveum, N. E., & Neumark, D. M. 2003, J. Chem. Phys., 119, 5311

Rosch, D., Caravan, R. L., Taatjes, C. A., et al. 2021, J. Phys. Chem. A., 125, 7920

Rosi, M., Mancini, L., Skouteris, D., et al. 2018, Chem. Phys. Lett., 695, 87

Roueff, E., Alekseyev, A. B., & Le Bourlot, J. 2014, A&A, 566, A30

Russell, C. T., Luhmann, J. G., & Strangeway, R. J. 2006, Planet. Space Sci., 54, 1482

Sabatini, G., Bovino, S., Giannetti, A., et al. 2020, A&A, 644, A34

Sakai, N., Sakai, T., & Yamamoto, S. 2008, ApJ, 673, L71

Sakai, N., Shiino, T., Hirota, T., Sakai, T., & Yamamoto, S. 2010, ApJ, 718, L49

Sauval, A. 1969, Solar Phys., 10, 319

Savee, J. D., Soorkia, S., Welz, O., et al. 2012, J. Chem. Phys., 136, 134307

Savee, J. D., Száray, B., Welz, O., Taatjes, C. A., & Osborn, D. L. 2021, J. Phys. Chem. A., 125, 3874

Saxon, R., Lengsfield, B., & Liu, B. 1983, J. Chem. Phys., 78, 312

Schwell, M., Jochims, H.-W., Baumgärtel, H., Dulieu, F., & Leach, S. 2006, Planet. Space Sci., 54, 1073

Schwell, M., Gaie-Levrel, F., Benilan, Y., et al. 2013, EAS Publ. Ser., 58, 301

Shaw, M. F., Sztaray, B., Whalley, L. K., et al. 2018, Nat. Commun., 9, 2584

Shi, X., Yin, Q.-Z., Gao, H., et al. 2017, ApJ, 850, 48

Shi, X., Gao, H., Yin, Q.-Z., et al. 2018, J. Phys. Chem. A., 122, 8136

Shin, S. K., Han, E. J., & Kim, H. L. 1998, J. Photochem. Photobiol. A, 118, 71

Silsbee, K., & Ivlev, A. V. 2019, ApJ, 879, 14

Silsbee, K., Ivlev, A. V., Padovani, M., & Caselli, P. 2018, ApJ, 863, 188

Simon, B. 2000, J. Math. Phys., 41, 3523

Singleton, D., Paraskevopoulos, G., & Irwin, R. 1987, J. Photochem., 37, 209

Singleton, D. L., Paraskevopoulos, G., & Irwin, R. S. 1989, Res. Chem. Intermed., 12, 1

Singleton, D. L., Paraskevopoulos, G., & Irwin, R. S. 1990, J. Phys. Chem., 94, 695

Skinner, D., & Wise, J. H. 2020, MNRAS, 492, 4386

Smith, W., & Liszt, H. 1971, J. Quant. Spectr. Rad. Transf., 11, 45

Song, Y., Gao, H., Chang, Y. C., et al. 2016, ApJ, 819, 23

Spencer, J. R., Jessup, K. L., McGrath, M. A., Ballester, G. E., & Yelle, R. 2000, Science, 288, 1208

Stark, G., Yoshino, K., & Smith, P. 1987, J. Mol. Spectr., 124, 420

Stark, G., Herde, H., Lyons, J. R., et al. 2018, J. Chem. Phys., 148, 244302

Stecher, T., & Williams, D. 1967, ApJ, 149, L29

Sternberg, A., & Dalgarno, A. 1995, ApJS, 99, 565

Sternberg, A., Gurman, A., & Bialy, S. 2021, ApJ, 920, 83

Suto, M., Wang, X., & Lee, L. C. 1988a, J. Phys. Chem., 92, 3764

Suto, M., Ye, C., & Lee, L. C. 1988b, J. Chem. Phys., 89, 6555

Taatjes, C. A., Hansen, N., Osborn, D. L., et al. 2008, Phys. Chem. Chem. Phys., 10, 20

Tabayashi, K., Aoyama, J.-i., Matsui, M., Hino, T., & Saito, K. 1999, J. Chem. Phys., 110, 9547

Tabone, B., Godard, B., des Forets, G. P., Cabrit, S., & van Dishoeck, E. F. 2020, A&A, 636, A60

Tabone, B., van Hemert, M. C., van Dishoeck, E. F., & Black, J. H. 2021, A&A, 650, A192

Talbi, D., & Ellinger, Y. 1996, Chem. Phys. Lett., 263, 385

Tang, X., Zhou, X., Sun, Z., et al. 2014, J. Chem. Phys., 140, 044312

Tang, X., Garcia, G. A., & Nahon, L. 2015a, J. Phys. Chem. A., 119, 5942

Tang, X., Garcia, G. A., Gil, J.-F., & Nahon, L. 2015b, Rev. Sci. Instrum., 86

Tang, X., Lin, X., Zhang, W., Garcia, G. A., & Nahon, L. 2016, Phys. Chem. Chem. Phys., 18, 23923

Tennyson, J., Lodi, L., McKemmish, L. K., & Yurchenko, S. N. 2016a, J. Phys. B., 49, 102001

Tennyson, J., Yurchenko, S. N., Al-Refaie, A. F., et al. 2016b, J. Mol. Spectr., 327, 73

Tenorio, B. N. C., Nascimento, M. A. C., & Rocha, A. B. 2019, J. Chem. Phys., 150, 154308

Thaddeus, P., Gottlieb, C. A., Hjalmarson, A., et al. 1985a, ApJ, 294, L49

Thaddeus, P., Vrtilek, J. M., & Gottlieb, C. A. 1985b, ApJ, 299, L63

Tielens, A. G. M. 2013, Rev. Mod. Phys., 85, 1021

Tielens, A., & Hollenbach, D. 1985, ApJ, 291, 722

Tinetti, G., Drossart, P., Eccleston, P., et al. 2018, Exp. Astron., 46, 135

Toffoli, D., & Lucchese, R. R. 2004, J. Chem. Phys., 120, 6010

Toulson, B. W., Kapnas, K. M., Fishman, D. A., & Murray, C. 2017, Phys. Chem. Chem. Phys., 19, 14276

Tranter, R. S., Lynch, P. T., & Yang, X. 2013, Proc. Combust. Inst., 34, 591

Tychoniec, Ł., van Dishoeck, E. F., van 't Hoff, M. L. R., et al. 2021, A&A, 655, A65

Urbain, X., Dochain, A., Marion, R., Launoy, T., & Loreau, J. 2019, Philos. Trans. Royal Soc. A, 377, 20180399

van der Wiel, M. H. D., Jacobsen, S. K., Jorgensen, J. K., et al. 2019, A&A, 626, A93

Van de Sande, M., & Millar, T. J. 2022, MNRAS, 510, 1204

van Dishoeck, E. F. 1987, J. Chem. Phys., 86, 196

van Dishoeck, E. F. 1988, Astrophys. Space Sci. Lib., 146, 49

van Dishoeck, E. F. 2004, ARA&A, 42, 119

van Dishoeck, E. F. 2014, Faraday Discuss., 168, 9

van Dishoeck, E. F., & Dalgarno, A. 1984a, Icarus, 59, 305

van Dishoeck, E. F., & Dalgarno, A. 1984b, ApJ, 277, 576

van Dishoeck, E. F., & Visser, R. 2015, in Laboratory Astrochemistry: From Molecules through Nanoparticles to Grains (Weinheim: Wiley-VCH)

van Dishoeck, E., van Hemert, M., Allison, A., & Dalgarno, A. 1984, J. Chem. Phys., 81, 5709

van Dishoeck, E. F., Jonkheid, B., & van Hemert, M. C. 2006, Faraday Discuss., 133, 231

van Dishoeck, E. F., Herbst, E., & Neufeld, D. A. 2013, Chem. Rev., 113, 9043

van Hemert, M., & van Dishoeck, E. 2008, Chem. Phys., 343, 292

van 't Hoff, M. L. R., Walsh, C., Kama, M., Facchini, S., & van Dishoeck, E. F. 2017, A&A, 599, A101

van 't Hoff, M. L. R., Persson, M. V., Harsono, D., et al. 2018, A&A, 613, A29

van 't Hoff, M. L. R., Dishoeck, v. E. F., Jørgensen, J. K., & Calcutt, H. 2020, A&A, 633, A7

van 't Hoff, M. L. R., Harsono, D., van Gelder, M. L., et al. 2022, ApJ, 924, 5

Vaupre, S., Hily-Blant, P., Ceccarelli, C., et al. 2014, A&A, 568, A50

Vega, M. V., Lavín, C., Velasco, A. M., & Martín, I. 2010, Theor. Chem. Acc., 127, 411

Venot, O., Rocchetto, M., Carl, S., Hashim, A. R., & Decin, L. 2016, ApJ, 830, 77
Öberg, K. I., & Bergin, E. A. 2021, Phys. Rep., 893, 1

Okabe, H. 1970, J. Chem. Phys., 53, 3507

Osborn, D. L., Zou, P., Johnsen, H., et al. 2008, Rev. Sci. Instrum., 79, 104103

Osted, A., Kongsted, J., & Christiansen, O. 2005, J. Phys. Chem. A., 109, 1430

Padial, N., Collins, L., & Schneider, B. 1985, ApJ, 298, 369

Padovani, M., & Galli, D. 2011, A&A, 530, A109

Padovani, M., Galli, D., & Glassgold, A. E. 2009, A&A, 501, 619

Padovani, M., Hennebelle, P., & Galli, D. 2013, A&A, 560, A114

Padovani, M., Marcowith, A., Hennebelle, P., & Ferrière, K. 2016, A&A, 590, A8

Padovani, M., Galli, D., Ivlev, A., Caselli, P., & Ferrara, A. 2018a, A&A, 619, A144

Padovani, M., Ivlev, A. V., Galli, D., & Caselli, P. 2018b, A&A, 614, A111

Padovani, M., Ivlev, A. V., Galli, D., et al. 2020, Space Sci. Rev., 216, 29

Pan, Z., Bodi, A., Bokhoven, v. J. A., & Hemberger, P. 2022, Phys. Chem. Chem. Phys., 24, 3655

Parise, B., Bergman, P., & Du, F. 2012, A&A, 541, A11

Petrignani, A., Bing, D., Novotny, O., et al. 2010, J. Phys. Chem. A., 114, 4864

Pety, J., Gratier, P., Guzmán, V., et al. 2012, A&A, 548, A68

Pezzella, M., Yurchenko, S. N., & Tennyson, J. 2021, Phys. Chem. Chem. Phys., 23, 16390

Pezzella, M., Tennyson, J., & Yurchenko, S. N. 2022, MNRAS, 514, 4413

Phan, V. H. M., Morlino, G., & Gabici, S. 2018, MNRAS, 480, 5167

Phan, V. H. M., Schulze, F., Mertsch, P., Recchia, S., & Gabici, S. 2021, Phys. Rev. Lett., 127, 141101

Phuong, N. T., Chapillon, E., Majumdar, L., et al. 2018, A&A, 616, A5

Pieper, J., Schmitt, S., Hemken, C., et al. 2018, Z. Phys. Chem. Intern. J. Res. Phys. Chem., 232, 153

Platzman, R. 1962, Radiat. Res., 16, 419

Podio, L., Lefloch, B., Ceccarelli, C., Codella, C., & Bachiller, R. 2014, A&A, 565, A64

Ponzi, A., Angeli, C., Cimiraglia, R., Coriani, S., & Decleva, P. 2014, J. Chem. Phys., 140, 204304

Pouilly, B., Robbe, J., Schamps, J., & Roueff, E. 1983, J. Phys. B., 16, 437

Pouilly, J. C., Schermann, J. P., Nieuwjaer, N., et al. 2010, Phys. Chem. Chem. Phys., 12, 3566

Pradhan, A. D., & Partridge, H. 1996, Chem. Phys. Lett., 255, 163

Prasad, S., & Tarafdar, S. 1983, ApJ, 267, 603

Qi, C., Öberg, K. I., Wilner, D. J., & Rosenfeld, K. A. 2013, ApJ, 765, L14

Qin, Z., Bai, T., & Liu, L. 2022, MNRAS, 516, 550

Qu, Q., Yurchenko, S. N., & Tennyson, J. 2022, J. Chem. Theory Comput., 18, 1808

Recchia, S., Phan, V. H. M., Biswas, S., & Gabici, S. 2019, MNRAS, 485, 2276

Resende, S. M., & Ornellas, F. R. 2001, J. Chem. Phys., 115, 2178

Reusch, E., Holzmeier, F., Constantinidis, P., Hemberger, P., & Fischer, I. 2017, Angew. Chem. Int. Ed., 56, 8000

Riaz, B., Thi, W.-F., & Caselli, P. 2019, MNRAS, 483, 1139

Rizzo, J. R., Guente, A., & Garcia-Burlo, S. 2005, ASP Conf. Ser., 344, 184

Roberge, W. G., Jones, D., Lepp, S., & Dalgarno, A. 1991, ApJS, 77, 287

Robertson, I. P., Cravens, T. E., Waite, J. H., et al. 2009, Planet. Space Sci., 57, 1834

Robinson, J. C., Sveum, N. E., & Neumark, D. M. 2003, J. Chem. Phys., 119, 5311

Rosch, D., Caravan, R. L., Taatjes, C. A., et al. 2021, J. Phys. Chem. A., 125, 7920

Rosi, M., Mancini, L., Skouteris, D., et al. 2018, Chem. Phys. Lett., 695, 87

Roueff, E., Alekseyev, A. B., & Le Bourlot, J. 2014, A&A, 566, A30

Russell, C. T., Luhmann, J. G., & Strangeway, R. J. 2006, Planet. Space Sci., 54, 1482

Sabatini, G., Bovino, S., Giannetti, A., et al. 2020, A&A, 644, A34

Sakai, N., Sakai, T., & Yamamoto, S. 2008, ApJ, 673, L71

Sakai, N., Shiino, T., Hirota, T., Sakai, T., & Yamamoto, S. 2010, ApJ, 718, L49

Sauval, A. 1969, Solar Phys., 10, 319

Savee, J. D., Soorkia, S., Welz, O., et al. 2012, J. Chem. Phys., 136, 134307

Savee, J. D., Száray, B., Welz, O., Taatjes, C. A., & Osborn, D. L. 2021, J. Phys. Chem. A., 125, 3874

Saxon, R., Lengsfield, B., & Liu, B. 1983, J. Chem. Phys., 78, 312

Schwell, M., Jochims, H.-W., Baumgärtel, H., Dulieu, F., & Leach, S. 2006, Planet. Space Sci., 54, 1073

Schwell, M., Gaie-Levrel, F., Benilan, Y., et al. 2013, EAS Publ. Ser., 58, 301

Shaw, M. F., Sztaray, B., Whalley, L. K., et al. 2018, Nat. Commun., 9, 2584

Shi, X., Yin, Q.-Z., Gao, H., et al. 2017, ApJ, 850, 48

Shi, X., Gao, H., Yin, Q.-Z., et al. 2018, J. Phys. Chem. A., 122, 8136

Shin, S. K., Han, E. J., & Kim, H. L. 1998, J. Photochem. Photobiol. A, 118, 71

Silsbee, K., & Ivlev, A. V. 2019, ApJ, 879, 14

Silsbee, K., Ivlev, A. V., Padovani, M., & Caselli, P. 2018, ApJ, 863, 188

Simon, B. 2000, J. Math. Phys., 41, 3523

Singleton, D., Paraskevopoulos, G., & Irwin, R. 1987, J. Photochem., 37, 209

Singleton, D. L., Paraskevopoulos, G., & Irwin, R. S. 1989, Res. Chem. Intermed., 12, 1

Singleton, D. L., Paraskevopoulos, G., & Irwin, R. S. 1990, J. Phys. Chem., 94, 695

Skinner, D., & Wise, J. H. 2020, MNRAS, 492, 4386

Smith, W., & Liszt, H. 1971, J. Quant. Spectr. Rad. Transf., 11, 45

Song, Y., Gao, H., Chang, Y. C., et al. 2016, ApJ, 819, 23

Spencer, J. R., Jessup, K. L., McGrath, M. A., Ballester, G. E., & Yelle, R. 2000, Science, 288, 1208

Stark, G., Yoshino, K., & Smith, P. 1987, J. Mol. Spectr., 124, 420

Stark, G., Herde, H., Lyons, J. R., et al. 2018, J. Chem. Phys., 148, 244302

Stecher, T., & Williams, D. 1967, ApJ, 149, L29

Sternberg, A., & Dalgarno, A. 1995, ApJS, 99, 565

Sternberg, A., Gurman, A., & Bialy, S. 2021, ApJ, 920, 83

Suto, M., Wang, X., & Lee, L. C. 1988a, J. Phys. Chem., 92, 3764

Suto, M., Ye, C., & Lee, L. C. 1988b, J. Chem. Phys., 89, 6555

Taatjes, C. A., Hansen, N., Osborn, D. L., et al. 2008, Phys. Chem. Chem. Phys., 10, 20

Tabayashi, K., Aoyama, J.-i., Matsui, M., Hino, T., & Saito, K. 1999, J. Chem. Phys., 110, 9547

Tabone, B., Godard, B., des Forets, G. P., Cabrit, S., & van Dishoeck, E. F. 2020, A&A, 636, A60

Tabone, B., van Hemert, M. C., van Dishoeck, E. F., & Black, J. H. 2021, A&A, 650, A192

Talbi, D., & Ellinger, Y. 1996, Chem. Phys. Lett., 263, 385

Tang, X., Zhou, X., Sun, Z., et al. 2014, J. Chem. Phys., 140, 044312

Tang, X., Garcia, G. A., & Nahon, L. 2015a, J. Phys. Chem. A., 119, 5942

Tang, X., Garcia, G. A., Gil, J.-F., & Nahon, L. 2015b, Rev. Sci. Instrum., 86

Tang, X., Lin, X., Zhang, W., Garcia, G. A., & Nahon, L. 2016, Phys. Chem. Chem. Phys., 18, 23923

Tennyson, J., Lodi, L., McKemmish, L. K., & Yurchenko, S. N. 2016a, J. Phys. B., 49, 102001

Tennyson, J., Yurchenko, S. N., Al-Refaie, A. F., et al. 2016b, J. Mol. Spectr., 327, 73

Tenorio, B. N. C., Nascimento, M. A. C., & Rocha, A. B. 2019, J. Chem. Phys., 150, 154308

Thaddeus, P., Gottlieb, C. A., Hjalmarson, A., et al. 1985a, ApJ, 294, L49

Thaddeus, P., Vrtilek, J. M., & Gottlieb, C. A. 1985b, ApJ, 299, L63

Tielens, A. G. M. 2013, Rev. Mod. Phys., 85, 1021

Tielens, A., & Hollenbach, D. 1985, ApJ, 291, 722

Tinetti, G., Drossart, P., Eccleston, P., et al. 2018, Exp. Astron., 46, 135

Toffoli, D., & Lucchese, R. R. 2004, J. Chem. Phys., 120, 6010

Toulson, B. W., Kapnas, K. M., Fishman, D. A., & Murray, C. 2017, Phys. Chem. Chem. Phys., 19, 14276

Tranter, R. S., Lynch, P. T., & Yang, X. 2013, Proc. Combust. Inst., 34, 591

Tychoniec, Ł., van Dishoeck, E. F., van 't Hoff, M. L. R., et al. 2021, A&A, 655, A65

Urbain, X., Dochain, A., Marion, R., Launoy, T., & Loreau, J. 2019, Philos. Trans. Royal Soc. A, 377, 20180399

van der Wiel, M. H. D., Jacobsen, S. K., Jorgensen, J. K., et al. 2019, A&A, 626, A93

Van de Sande, M., & Millar, T. J. 2022, MNRAS, 510, 1204

van Dishoeck, E. F. 1987, J. Chem. Phys., 86, 196

van Dishoeck, E. F. 1988, Astrophys. Space Sci. Lib., 146, 49

van Dishoeck, E. F. 2004, ARA&A, 42, 119

van Dishoeck, E. F. 2014, Faraday Discuss., 168, 9

van Dishoeck, E. F., & Dalgarno, A. 1984a, Icarus, 59, 305

van Dishoeck, E. F., & Dalgarno, A. 1984b, ApJ, 277, 576

van Dishoeck, E. F., & Visser, R. 2015, in Laboratory Astrochemistry: From Molecules through Nanoparticles to Grains (Weinheim: Wiley-VCH)

van Dishoeck, E., van Hemert, M., Allison, A., & Dalgarno, A. 1984, J. Chem. Phys., 81, 5709

van Dishoeck, E. F., Jonkheid, B., & van Hemert, M. C. 2006, Faraday Discuss., 133, 231

van Dishoeck, E. F., Herbst, E., & Neufeld, D. A. 2013, Chem. Rev., 113, 9043

van Hemert, M., & van Dishoeck, E. 2008, Chem. Phys., 343, 292

van 't Hoff, M. L. R., Walsh, C., Kama, M., Facchini, S., & van Dishoeck, E. F. 2017, A&A, 599, A101

van 't Hoff, M. L. R., Persson, M. V., Harsono, D., et al. 2018, A&A, 613, A29

van 't Hoff, M. L. R., Dishoeck, v. E. F., Jørgensen, J. K., & Calcutt, H. 2020, A&A, 633, A7

van 't Hoff, M. L. R., Harsono, D., van Gelder, M. L., et al. 2022, ApJ, 924, 5

Vaupre, S., Hily-Blant, P., Ceccarelli, C., et al. 2014, A&A, 568, A50

Vega, M. V., Lavín, C., Velasco, A. M., & Martín, I. 2010, Theor. Chem. Acc., 127, 411

Venot, O., Rocchetto, M., Carl, S., Hashim, A. R., & Decin, L. 2016, ApJ, 830, 77
Venot, O., Bénilan, Y., Fray, N., et al. 2018a, A&A, 609, A34

Venot, O., Drummond, B., Miguel, Y., et al. 2018b, Exp. Astron., 46, 101

Visscher, C., Lodders, K., & Fegley, B. 2010, ApJ, 716, 1060

Visser, R., van Dishoeck, E. F., & Black, J. H. 2009, A&A, 503, 323

Visser, R., Bruderer, S., Cazzoletti, P., et al. 2018, A&A, 615, A75

Vuitton, V., Yelle, R. V., & Anicich, V. G. 2006, ApJ, 647, L175

Walmsley, C. M., Pineau des Forêts, G., & Flower, D. R. 1999, A&A, 342, 542

Walsh, C., Nomura, H., Millar, T. J., & Aikawa, Y. 2012, ApJ, 747, 114

Walsh, C., Nomura, H., & van Dishoeck, E. F. 2015, A&A, 582, A88

Wang, J., Yang, B., Cool, T. A., & Hansen, N. 2010, Int. J. Mol., 292, 14

Wang, K., Liu, J., Wang, Y., Yang, C., & Liu, Y. 2021, A&A, 654, A172

Weingartner, J. C., & Draine, B. T. 2001a, ApJ, 548, 296

Weingartner, J. C., & Draine, B. T. 2001b, ApJ, 553, 581

Weingartner, J. C., & Draine, B. T. 2001c, ApJ, 563, 842

Weingartner, J. C., & Draine, B. T. 2001d, ApJS, 134, 263

Wheeler, M. D., Newman, S. M., & Orr-Ewing, A. J. 1998, J. Chem. Phys., 108, 6594

Wolcott-Green, J., & Haiman, Z. 2019, MNRAS, 484, 2467

Wolfire, M. G., Vallini, L., & Chevance, M. 2022, ARA&A, 60, 247

Woods, T. N., Prinz, D. K., Rottman, G. J., et al. 1996, J. Geophys. Res. Atmos., 101, 9541

Woods, P. M., Millar, T. J., Herbst, E., & Zijlstra, A. A. 2003, A&A, 402, 189

Wu, X., Zhou, X., Hemberger, P., & Bodi, A. 2019, Phys. Chem. Chem. Phys., 21, 22238

Xu, H., & Pratt, S. T. 2013, J. Phys. Chem. A., 117, 9331

Xu, Z., Luo, N., Federman, S. R., et al. 2019, ApJ, 882, 86

Yamaguchi, Y., Hoffman, B. C., Stephens, J. C., & Schaefer, H. F. 1999, J. Phys. Chem. A., 103, 7701

Yamamoto, S., Saito, S., Ohishi, M., et al. 1987, ApJ, 322, L55

Yang, B., Wang, J., Cool, T. A., et al. 2012, Int. J. Mol., 309, 118

Yang, C.-H., Bhattacharyya, S., Liu, L., Fang, W.-h., & Liu, K. 2020, Chem. Sci., 11, 6423

Yang, C.-H., Bhattacharyya, S., & Liu, K. 2021, J. Phys. Chem. A., 125, 6450

Yencha, A. J., Siggel-King, M. R., King, G. C., Malins, A. E., & Eypper, M. 2013, J. Electron. Spectros. Relat. Phenomena, 187, 65

Yoshida, H., & Mitsuke, K. 1994, J. Chem. Phys., 100, 8817

Yoshida, H., & Mitsuke, K. 1996, J. Electron. Spectros. Relat. Phenomena, 79, 487

Yurchenko, S. N., Lodi, L., Tennyson, J., & Stolyarov, A. V. 2016, Comput. Phys. Commun., 202, 262

Yurchenko, S. N., Al-Refaie, A. F., & Tennyson, J. 2018, A&A, 614, A131

Zahnle, K., Marley, M. S., Freedman, R. S., Lodders, K., & Fortney, J. J. 2009, ApJ, 701, L20

Zanchet, A., Agúndez, M., Herrero, V. J., Aguado, A., & Roncero, O. 2013, AJ, 146, 125

Zanchet, A., Lique, F., Roncero, O., Goicoechea, J. R., & Bulut, N. 2019, A&A, 626, A103

Zeng, S., Zhang, Q., Jiménez-Serra, I., et al. 2020, MNRAS, 497, 4896

Zhang, Z., Chen, Z., Huang, C., et al. 2014a, J. Phys. Chem. A., 118, 2413

Zhang, Z.-g., Chen, Z.-c., Zhan, C.-m., et al. 2014b, Chin. J. Chem. Phys., 27, 249

Zhang, Z.-g., Xin, M., Wu, Y.-n., et al. 2018a, Chin. J. Chem. Phys., 31, 735

Zhang, Z.-g., Xin, M., Zhao, S.-t., & Chen, Y. 2018b, Chin. J. Chem. Phys., 31, 27

Zhang, L., Shu, Y., Sun, S., & Truhlar, D. G. 2021, J. Chem. Phys., 154, 094310

Zheng, X., Song, Y., & Zhang, J. 2009, J. Phys. Chem. A., 113, 4604
Venot, O., Bénilan, Y., Fray, N., et al. 2018a, A&A, 609, A34

Venot, O., Drummond, B., Miguel, Y., et al. 2018b, Exp. Astron., 46, 101

Visscher, C., Lodders, K., & Fegley, B. 2010, ApJ, 716, 1060

Visser, R., van Dishoeck, E. F., & Black, J. H. 2009, A&A, 503, 323

Visser, R., Bruderer, S., Cazzoletti, P., et al. 2018, A&A, 615, A75

Vuitton, V., Yelle, R. V., & Anicich, V. G. 2006, ApJ, 647, L175

Walmsley, C. M., Pineau des Forêts, G., & Flower, D. R. 1999, A&A, 342, 542

Walsh, C., Nomura, H., Millar, T. J., & Aikawa, Y. 2012, ApJ, 747, 114

Walsh, C., Nomura, H., & van Dishoeck, E. F. 2015, A&A, 582, A88

Wang, J., Yang, B., Cool, T. A., & Hansen, N. 2010, Int. J. Mol., 292, 14

Wang, K., Liu, J., Wang, Y., Yang, C., & Liu, Y. 2021, A&A, 654, A172

Weingartner, J. C., & Draine, B. T. 2001a, ApJ, 548, 296

Weingartner, J. C., & Draine, B. T. 2001b, ApJ, 553, 581

Weingartner, J. C., & Draine, B. T. 2001c, ApJ, 563, 842

Weingartner, J. C., & Draine, B. T. 2001d, ApJS, 134, 263

Wheeler, M. D., Newman, S. M., & Orr-Ewing, A. J. 1998, J. Chem. Phys., 108, 6594

Wolcott-Green, J., & Haiman, Z. 2019, MNRAS, 484, 2467

Wolfire, M. G., Vallini, L., & Chevance, M. 2022, ARA&A, 60, 247

Woods, T. N., Prinz, D. K., Rottman, G. J., et al. 1996, J. Geophys. Res. Atmos., 101, 9541

Woods, P. M., Millar, T. J., Herbst, E., & Zijlstra, A. A. 2003, A&A, 402, 189

Wu, X., Zhou, X., Hemberger, P., & Bodi, A. 2019, Phys. Chem. Chem. Phys., 21, 22238

Xu, H., & Pratt, S. T. 2013, J. Phys. Chem. A., 117, 9331

Xu, Z., Luo, N., Federman, S. R., et al. 2019, ApJ, 882, 86

Yamaguchi, Y., Hoffman, B. C., Stephens, J. C., & Schaefer, H. F. 1999, J. Phys. Chem. A., 103, 7701

Yamamoto, S., Saito, S., Ohishi, M., et al. 1987, ApJ, 322, L55

Yang, B., Wang, J., Cool, T. A., et al. 2012, Int. J. Mol., 309, 118

Yang, C.-H., Bhattacharyya, S., Liu, L., Fang, W.-h., & Liu, K. 2020, Chem. Sci., 11, 6423

Yang, C.-H., Bhattacharyya, S., & Liu, K. 2021, J. Phys. Chem. A., 125, 6450

Yencha, A. J., Siggel-King, M. R., King, G. C., Malins, A. E., & Eypper, M. 2013, J. Electron. Spectros. Relat. Phenomena, 187, 65

Yoshida, H., & Mitsuke, K. 1994, J. Chem. Phys., 100, 8817

Yoshida, H., & Mitsuke, K. 1996, J. Electron. Spectros. Relat. Phenomena, 79, 487

Yurchenko, S. N., Lodi, L., Tennyson, J., & Stolyarov, A. V. 2016, Comput. Phys. Commun., 202, 262

Yurchenko, S. N., Al-Refaie, A. F., & Tennyson, J. 2018, A&A, 614, A131

Zahnle, K., Marley, M. S., Freedman, R. S., Lodders, K., & Fortney, J. J. 2009, ApJ, 701, L20

Zanchet, A., Agúndez, M., Herrero, V. J., Aguado, A., & Roncero, O. 2013, AJ, 146, 125

Zanchet, A., Lique, F., Roncero, O., Goicoechea, J. R., & Bulut, N. 2019, A&A, 626, A103

Zeng, S., Zhang, Q., Jiménez-Serra, I., et al. 2020, MNRAS, 497, 4896

Zhang, Z., Chen, Z., Huang, C., et al. 2014a, J. Phys. Chem. A., 118, 2413

Zhang, Z.-g., Chen, Z.-c., Zhan, C.-m., et al. 2014b, Chin. J. Chem. Phys., 27, 249

Zhang, Z.-g., Xin, M., Wu, Y.-n., et al. 2018a, Chin. J. Chem. Phys., 31, 735

Zhang, Z.-g., Xin, M., Zhao, S.-t., & Chen, Y. 2018b, Chin. J. Chem. Phys., 31, 27

Zhang, L., Shu, Y., Sun, S., & Truhlar, D. G. 2021, J. Chem. Phys., 154, 094310

Zheng, X., Song, Y., & Zhang, J. 2009, J. Phys. Chem. A., 113, 4604
## Appendix A: Integrated flux of radiation fields

<table><caption>**Table A.1.** Integrated fluxes of the radiation fields and conversion factor used to normalize them.</caption><thead><tr><th>Radiation field</th><th>Integrated flux x 10<sup>-19</sup>)</th><th>Normalization factor x 10<sup>8</sup></th></tr></thead><tbody><tr><td>ISRF</td><td>5.15</td><td>5.05</td></tr><tr><td>Mathis</td><td>3.48</td><td>7.47</td></tr><tr><td>4000 K</td><td>5.12</td><td>5.08</td></tr><tr><td>10 000 K</td><td>5.11</td><td>5.08</td></tr><tr><td>20 000 K</td><td>5.14</td><td>5.06</td></tr><tr><td>Lyman-α</td><td>5.11</td><td>5.09</td></tr><tr><td>Solar</td><td>5.14</td><td>5.06</td></tr><tr><td>TW Hya</td><td>5.13</td><td>5.07</td></tr></tbody></table>

**Notes.** The fluxes used here to compute photorates in the database were used on a 0.001 nm grid and the conversion factor used to normalize the energy intensities of the radiation fields is in W cm⁻².
# Appendix A: Integrated flux of radiation fields

<table><caption>**Table A.1.** Integrated fluxes of the radiation fields and conversion factor used to normalize them.</caption><thead><tr><th>Radiation field</th><th>Integrated flux x 10<sup>-19</sup>)</th><th>Normalization factor x 10<sup>8</sup></th></tr></thead><tbody><tr><td>ISRF</td><td>5.15</td><td>5.05</td></tr><tr><td>Mathis</td><td>3.48</td><td>7.47</td></tr><tr><td>4000 K</td><td>5.12</td><td>5.08</td></tr><tr><td>10 000 K</td><td>5.11</td><td>5.08</td></tr><tr><td>20 000 K</td><td>5.14</td><td>5.06</td></tr><tr><td>Lyman-α</td><td>5.11</td><td>5.09</td></tr><tr><td>Solar</td><td>5.14</td><td>5.06</td></tr><tr><td>TW Hya</td><td>5.13</td><td>5.07</td></tr></tbody></table>

**Notes.** The fluxes used here to compute photorates in the database were used on a 0.001 nm grid and the conversion factor used to normalize the energy intensities of the radiation fields is in W cm⁻².