dataesr/scientific-paragraphs-categorization huggingface dataset:
Recently a new program, DUO, was developed to solve the coupled nuclear motion problem for diatomic molecules  (Yurchenko et al. 2016). The main method of solving the radial equation is called discrete variable representation (DVR) which has been independently applied to the one-dimensional Schrödinger equation  (Guardiola & Ros 1982b,a). In this method the R coordinate is truncated to an interval and discretized in a grid of N p uniformly spaced points. This transforms the Schrödinger equation to an ordinary matrix eigenvalue problem where the N p × N p real symmetric Hamiltonian matrix is diagonalized. This method gives a very fast convergence of the calculated energies and wave functions with respect to the number of grid points N p. By coupling the potential energy curves from DUO with another program developed by the same group, ExoCross  (Yurchenko et al.
2018) , photodissociation cross sections at various temperatures can be obtained  (Pezzella et al. 2021). This methodology has been applied to HF and HCl to obtain hightemperature VUV photodissociation cross sections  (Pezzella et al. 2022). This work was very quickly revisited by a different group who used a different transition dipole moment in dealing with one of the electronic transitions in HCl which led to significant differences in the cross sections at high temperatures toward longer wavelengths  (Qin et al. 2022). The reasoning behind this choice is that in the work by Pezzella et al. , they used a tabulated TDM value published previously  (Engin et al. 2012 ) which appears to have a typographical error. Overall, the results are consistent with what was previously included in the database.
Other notable results making use of DUO include the updated photodissociation cross sections of CS  (Xu et al. 2019). In this work, the authors used a coupled-channel Schrödinger equation (CSE) to investigate the predissociation mechanisms of CS where over twenty electronic states were accounted for, but special attention was paid to the B 1 Σ + and C 1 Σ + states which are found to be strongly predissociative. To calculate the photodissociation cross section they employed the program PyDiatomic  (Gibson 2016)  which also uses the Numerov method  (Johnson 1978). It is worth briefly noting some recent advances concerning photoionization cross sections. Provided that the electronic A25, page 5 of 32  A&A 675, A25 (2023)  structure is known exactly, molecular cross sections can be calculated as described above, but this is only the case for atoms and diatomics.
Dust and line shielding The last database update included shielding functions and gave a detailed overview of the formulations accounting for dust and line shielding  (Heays et al. 2017 ). These calculations are also performed for the updated cross sections, and we present a brief overview of the calculations but refer to the previous work by Heays et al. for a more detailed discussion. Molecules embedded inside interstellar clouds, protoplanetary disks or other such objects with large densities and a high dust content, are at least partially shielded from VUV radiation. Equation (  4 ) gave the unattenuated photodestruction rate and so to account for the shielding materials in these objects we recalculate the rate as: σ pd (λ)exp[-τ dust (λ, N H+2H 2 ) - x=H,H 2 ,self N X σ abs X (λ)]I(λ)dλ.
Modeling dust shielding in other geometries will require more specific radiative transfer calculations than those used here. Shielding functions for photodissociation and photoionization have been calculated for all the species in the database and are available online in tabulated form. The shielding functions are often plotted as a function of the visual extinction (A V ) in an interstellar cloud for simpler use. These can be formulated as one-parameter exponential curves  (van Dishoeck et al. 2006) : θ(A V ) = exp(-γ exp A V ) (7) or second order exponential integrals  (Neufeld & Wolfire 2009; Roueff et al. 2014) : θ(A V ) = E 2 (-γ E 2 A V ). (8) A further reduction of the shielding function can be accomplished by introducing an exponential-decay parameter (γ f it ) and A25, page 6 of 32  Hrodmarsson, H.
R. , and van Dishoeck, E. F. : A&A proofs,  an effective unshielded rate (k f it 0 ) so that the depth-dependent photodestruction rate is: k = k f it 0 exp(-γ f it A V ) (9) which leads to the shielding function: θ(A V ) = k f it 0 /k 0 = exp(-γ f it A V ). ( 10 ) The values of γ E 2 , γ exp , γ f it , and k f it 0 , for both photodissociation and photoionization are tabulated for each updated or added cross section in the database and can be downloaded online. The dust-shielding-dependent photodissociation and photoionization rates were calculated using the optical properties of a dust population assuming one particular composition and size distribution which were obtained from the mixed grain-size and composition model built, developed and tested by Draine et al. (Draine & Lee 1984; Li & Draine 2001; Weingartner & Draine 2001a,b,c,d; Draine 2003a,b,c; Draine & Tan 2003) , specifically their "RV = 3.
2021). Other factors may be important for the cosmic ray ionization rate such as how cosmic ray diffusion operates in molecular clouds; through freestreaming or diffusive propagation  (Silsbee & Ivlev 2019) , and how diffusive shock acceleration can drive high ionization rates and synchrotron emissions toward protostellar sources  (Padovani et al. 2016 ). These and other recent advances and current open questions concerning cosmic rays have recently been reviewed  (Padovani et al. 2020; Gabici 2022). The cosmic ray ionization rate adopted in the database is ξ H 2 = 10 -16 s -1 H -1 2. All cosmic ray induced photodestruction rates can be adapted to other values of ξ H 2 by simple scaling. Other relevant parameters that were assumed are the following: x(H) = 10 -4 , x(N 2 ) = x(CO) = 10 -5 , ortho-H 2 :para-H 2 = 0:1.
These are equivalent to those used in the previous database update. Although most cosmic ray generated photons are absorbed by dust grains, there is a fraction that drives photodissociation and photoionization of atoms or molecules, X. This fraction is given by: p X (λ) = x X σ diss/ion X x dust σ abs dust (λ) + j x j σ abs j (λ). ( 13 ) Here, σ diss/ion X is the photodissociation or photoionization cross section of species X, and the denominator sums the photoabsorption cross sections of all dust and gas species. The probability of a cosmic-ray-generated UV photon being absorbed by a dust grain or any gaseous molecule is wavelength-dependent through the relevant cross sections utilized in Eq. (  13 ). The rate of a particular photodestruction process for species X due to cosmic ray ionization produced photons is then: k X = 1 x X R(λ)p X (λ)dλ.
Temperature effects The original objective of the database was to provide cross sections to accurately simulate UV-driven photoprocesses in the interstellar medium where temperature effects are negligible. As such, it is worth briefly addressing limitations of the applicability of the data in this database. These concern high-temperatures in certain radiation fields, but these effects are usually molecule dependent and should be assessed on a molecule-to-molecule basis. As shown in the works of both  Pezzella et al. (2022)  and  Qin et al. (2022) , photodissociation rates of HF and HCl under ISRF conditions are negligibly affected by the high-temperature cross sections in comparison to colder temperatures in molecular clouds. As the effects of high temperatures are principally observed as large increases in the cross sections toward longer wavelengths, the photodissociation rates are particularly temperature-sensitive in radiation fields with greater intensities toward longer wavelengths.
For instance, under a 4000 K blackbody radiation field, the photodissociation rates of HF and HCl derived at excitation temperatures between 0 K and 10 000 K are found to increase negligibly between 0 K and 2000 K, but by two orders of magnitude between 2000 K and 10 000 K  (Qin et al. 2022 ). In the cases of high-temperature exoplanet atmosphere, a caveat is therefore warranted in using the data from this database. Currently, high-temperature photodissociation cross sections are being computed and compiled in the EXOMOL database  (Tennyson et al. 2016b ) and UV absorption cross sections at various temperature ranges are being compiled in the HITRAN database  (Gordon et al. 2022 ), but at the time of writing only a handful of high-temperature cross section are available. These temperature dependent limitations have also been discussed in Sect.
Cross section database update All cross sections that have been added to the database (or updated) are presented. They are plotted in Figs. 1 2 3 4  each section their newly computed photorates are tabulated for each molecule along with comparisons to older values where applicable in Tables 1-33. In Table  34 , an overview of the database updates is presented along with an estimated rating of the uncertainty of the cross sections. We give four ratings: A+, A, B, and C, which correspond to accuracy within 20%, 30%, a factor of 2 and an order of magnitude, respectively. The new cross sections are presented in the same logical order as presented in the previous database update  (Heays et al. 2017).
H + 3 The VUV photodissociation of H + 3 has been investigated recently using three-dimensional imaging of the dissociation products  (Urbain et al. 2019). The potential energy surfaces of H + 3 exhibit a rich topology which results from the high degree of symmetry imposed by the indiscernibility of the protons, and the asymptotic degeneracy of its fragmentation channels which stems from it. In their seminal work on time-dependent wavepacket propagation, Kulander & Heller computed the photodissociation cross section of H + 3 in its absolute ground state  (Kulander & Heller 1978)  in which they found a maximum around 21 eV that starts growing in above 14 eV. This cross section is currently implemented in the database. The experimental dissociation threshold of H + 3 has, however, been measured to be 4.
CH (methylidyne) In the original publication of the database, an absorption/dissociation cross section of CH is included along with a tentative photoionization cross section. The photodissociation cross section is based on ab initio calculations (van Dishoeck 1987) and the included photoionization cross section was based on a photoelectron spectrum  (Barsuhn & Nesbet 1978). Recently, the photoion efficiency curve of CH was measured by mixing a CH 4 precursor diluted in He with F radicals to abstract the H atoms  (Gans et al. 2016). As CH was produced by means of a series of exothermic H-abstractions, some of the excess energy populated the v = 1, 2 levels of the neutral ground state, but these contribute negligibly to the measured total ion yield above the ionization threshold which is measured at 10.
C 2 H 3 (vinyl) The absorption cross section of the vinyl radical between 225 and 238 nm has been measured by  Fahr et al. (1998)  who obtain a maximum absorbance of 10 Mb at 225 nm. This is the only recorded cross section of the vinyl radical but an older absorption spectrum of the C 2 H 3 radical was recorded between 360 and 500 nm  (Hunziker et al. 1983 ). Their absorption spectrum has been fitted with several Gaussians and the highest peaks scaled to 10 Mb. The curve measured by  Fahr et al. (1998) , however, resembles the onset of a Gaussian peak and the curve steepness also compares well with the total ion yield recorded by  Garcia et al. (2021). Here we simulate an absorption with a Gaussian using the measurements by Fahr et al. which yields a maximum at 40 Mb around 200 nm. This intensity is comparable to other hydrocarbons in the database although further calculations and measurements of this radical would be of great interest.
Other work relevant to the photodissociation of C 2 H 3 includes a photodissociation study by  Ahmed et al. (1999)  who found the threshold for photodissociation of C 2 H 3 just above 1 eV (1240 nm). Up to 6 eV (207 nm) they find that the fragments formed involve a H atom and various electronically excited states of the C 2 H 3 planar form or the H 2 CC molecule. As with other photodissociation cross sections in the database that have been obtained by calculations, a baseline absorption of 0. 05 Mb from the dissociation threshold up to the Lyman-α limit at 91. 2 nm is added to the simulated cross section. The adiabatic ionization energy of the vinyl radical has been measured as 8. 462 eV (146. 5 nm)  (Wu et al. 2019 ). The photoionization of vinyl has been studied to include its first two excited states (ã + 3 A "′′ & Ã+ 1 A ′′ ) and its total ion yield was measured up to 12 eV (103 nm)  (Garcia et al.
C 2 H 5 (ethyl) The ethyl cation, C 2 H + 5 has been detected with the ROSINA probe on 67P along with C 2 H + 4 , C 2 H + 3 , C 2 H + 2 , and many others  (Beth et al. 2020 ) and is included here in the database for the first time. While no absolute photodissociation cross section has been recorded for the ethyl radical, its absorption spectrum was recorded by  Munk et al. (1986). They observed a broad absorption centered around 245 nm which originates from an excitation to the 3s Rydberg orbital whilst at smaller wavelengths, the 3p manifold is populated. No VUV absorption measurements have been recorded below 200 nm, but several studies on the photodissociation of C 2 H 5 have been reported which showcase the main dissociation pathway to be the loss of H and then different rearrangements of the C 2 H 4 moiety that are energy-dependent, for instance, the 3s manifold appears to produce ethene whilst the 3p manifold produces CH 3 CH  (Chicharro et al.
C 3 H 3 An important intermediate in combustion chemistry, the resonantly stabilized propargyl radical is included in the database. The absolute photoionization cross section of propargyl was measured by  Savee et al. (2012)  and the ionization energy has been measured as 8. 70053 eV (142. 502 nm)  (Jacovella et al. 2013 ). The photoionization cross section measurements by Savee were significantly larger than a previous measurements  (Robinson et al. 2003) , but were subsequently replicated and verified  (Xu & Pratt 2013). The photodissociation cross section of propargyl has been pieced together from several studies both experimental and theoretical. An absorption cross section was recorded which peaks around 12 Mb  (Fahr et al. 1997). The absorption spectrum of C 3 H 3 was also calculated by  Eisfeld (2006)    however, or photodissociation products in this wavelength range  (Deyerl et al.
2018; Harper et al. 2019 Harper et al. , 2020b ) using i 2 PEPICO 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.
HO 2 (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 experiments  (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.
NH 2 (amidogen) The photodissociation cross section of NH 2 was constructed 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 measured 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.
HNC (hydrogen isocyanide) HNC is a very tricky molecule to work in a laboratory setting. Hence, very few experimental studies exist which have investigated its physical and chemical properties. Although theoretically challenging as well, its photoabsorption/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 (CH 2 NH) 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 approximately 1.
CH 3 OCHO (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 S 1 electronically excited state leading to the formation of the methoxy (CH 3 O) and formyl (HCO) radicals  (Cui et al.
SH (mercapto) The photodissociation cross section of SH has been in 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.
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 in 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.
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 S 2 was previously made by scaling the photoionization efficiency curve measured by  Liao & Ng (1986).
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).
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).
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.
2010). This could likely be due to large C 2 H -photorates (Table  5 ), particularly in comparison to photodestruction rates of C 2 H (Table  4 ) which are on average 1-2 orders of magnitude smaller than that of C 2 H -. 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 HO 2 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 O 2 toward short wavelengths and the maximum of the H 2 O 2 cross section around 90 nm previously included in the database  (Heays et al. 2017). Curiously, the recently measured absolute cross section of the HO 2 radical is measured with a somewhat smaller maximum below 10 Mb.