九州大学大学院総合理工学府報告第 45 巻 1 号 25-30 頁 令和 5 年 9 月

Engineering Sciences Reports, Kyushu University
Vol. 45, No. 1, pp. 25-30, SEP, 2023

Branching Ratios of Recombination and
Neutralization Reactions in the Positive ion–
Negative Ion Reactions of Kr+ and Xe+ with C6F5Brand C6F5CF3- in the Flowing Afterglow
Masaharu TSUJI,*1,2† Hiroaki ISHIMI,*3 Keiko UTO,*1
Jun-Ichiro HAYASHI*1 and Takeshi TSUJI*4
E-mail of corresponding author: tsuji@cm.kyushu-u.ac.jp†(Received June 2, 2023, accepted June 13, 2023)
The positive ion–negative ion reactions of Kr+ and Xe+ with C6F5Br- and C6F5CF3- have been
spectroscopically studied in the He flowing afterglow. The branching ratios of recombination andneutralization reactions leading to RgX* excimers and excited Rg* atoms (Rg = Kr, Xe, X = Br, F),
respectively, were determined to be 0.14:0.86 and 1.00:0.00 for the Kr+/C6F5Br- and Xe+/C6F5Brreactions and 0.00:1.00 for both the Kr+/C6F5CF3- and Xe+/C6F5CF3- reactions. It was concluded thatelectron affinities of target molecules and dissociation energies of C6F5X- leading to X- play a significant
role in determining the branching ratio of ion–ion recombination and neutralization reactions.
-

Key words: Ion–ion reaction, Flowing afterglow, Emission spectroscopy, Kr+, Xe+, C6F5Br , C6F5CF3-

Recombination reaction, Neutralization reaction, Branching ratio, KrBr* excimer,
XeBr* excimer, Excited rare gas atoms

1.

Introduction

Because of the strong, long-range Coulomb
attractive force between the positive andnegative ions, ion–ion mutual recombination
reactions are characterized by large crosssections, as much as 10,000 Å2, at low
energies.1,2) Therefore, ion–ion recombination
reactions are an important loss process of ionsin natural and man-made plasmas involving
positive and negative ions. In most cases, thereaction is highly exothermic, so the products
may be electronically excited or evendissociated. The main aim of previous studies
was to determine the cross sections or reaction
rate constants.3-8) Little work has been carriedout on the product-state distributions in theion–ion reactions.
In order to obtain product-state distributions,
we have previously made optical spectroscopic*1 Institute for Materials Chemistry and Engineering,and Research and Education Center of GreenTechnology*2 Department of Molecular Science and Technology*3 Department of Molecular Science and Technology,
Graduate Student*4 Department of Materials Science, Shimane
University

studies on the ion–ion reactions between raregas cations (Rg+) and such negative ions as SF6and C6F5X- (X = F, Cl) using a flowing-afterglow
apparatus.9-17) We determined the branchingratios of recombination reaction leading to
RgX* excimer and neutralization reaction
leading to excited Rg* atoms. The branchingratiosbetweenrecombination
andneutralization reactions were 0.001:0.999,
0.00:1.00, 0.69:0.31, and 0.89:0.11 for the
Xe+/C6F6-,
Kr+/C6F5Cl-,
andKr+/C6F6-,
Xe+/C6F5Cl reactions, respectively.11,16)
In this study, ion–ion reactions of Kr+(2P1/2,3/2)
and Xe+(2P1/2,3/2) with C6F5Br- and C6F5CF3- arespectroscopically studied in the He flowing
afterglow.
The
branchingratiosofrecombination and neutralization reactions
leading to RgX* excimers and excited Rg*
atoms (Rg = Kr, Xe), respectively, aredetermined.
Rg+ + C6F5X- (X = Br, CF3)
→ RgX* + C6F5 (recombination),→ Rg* + C6F5X (neutralization).

(1a)
(1b)

Results obtained are compared with ourprevious data for the Rg+/C6F5X- (X = F, Cl)

Ion-ion recombination and neutralization reactions of Rg+ (Rg = Kr, Xe) with C6F5Br- and C6F5CF3- in the flowing afterglow

26

occurs at a relatively high He buffer gas
pressures of 2–10 Torr in the same flowingafterglow apparatus.21)

reactions.11,16)

2.

Experimental

2.1

Chemicals

Gaseous and liquid samples used in thisstudy were obtained from Japanese chemicalcompanies: He (purity >99.9999%, Taiyo
Sanso), Kr (99.995%, Nippon Sanso), Xe(99.99%, Nippon Sanso), C6F5Br (Kishida
Kagaku, 97%), and C6F5CF3 (Kishida Kagaku,98%). These samples were used without further
purification.
2.2

Apparatus and experimental procedures

The flowing-afterglow apparatus used in thisstudy was identical with that reported
previously.16,17) A mixture of He(23S), He+, andHe2+ was generated by a microwave dischargeof high purity He gas in a He flowing afterglow.
He+ and He2+ ions in the discharge flow were
removed by using a pair of ion-collector grids
placed between the discharge section and thereaction zone. A small amount of Kr or Xe gas
was added to the He flow 10 cm downstream
from the center of microwave discharge.
Positive Kr+(2P1/2,3/2) or Xe+(2P1/2,3/2) ion wereformed by the He(23S)/Kr or He(23S)/Xe
Penning ionization.
He(23S) + Kr → Kr+(2P1/2,3/2) + He + e-. (2)(k2 = 9.94 × 10-11 cm3 s-1 [Ref. 18)
He(23S) + Xe → Xe+(2P1/2,3/2) + He + e-. (3)(k3 = 1.24 × 10-10 cm3 s-1 [Ref. 18])
Further 10 cm downstream from the Kr or Xe
gas inlet, an electron attachment gas, C6F5Br
or C6F5CF3, was added, where negative C6F5Bror C6F5CF3- ion was formed as major products
by a fast electron attachment to these two gases.
(4a)
C6F5Br + e- → C6F5Br- (≥ 97%),(4b)→ Br- + C6F5 (≤ 3%).
(k4a + k4b = 8.3 × 10-8 cm3 s-1 [Ref. 19])
C6F5CF3 + e- → C6F5CF3-.
(k5 = 2.42 × 10-7 cm3 s-1 [Ref. 20])

Xe+(2P1/2,3/2) + Br- + He
→ XeBr(B,C,D) + He,→ Br* + Xe + He.

To suppress above three-body reaction, He
buffer gas pressure was maintained at a
relatively low pressure of 1.0 Torr in this study.
The emission, observed around the C6F5Br
or C6F5CF3 gas inlet, was dispersed in the 120–
840 nm region with McPherson 218 and Spex
1250M monochromators.
We used ionization potentials of Kr and Xe,electron affinities of C6F5Br or C6F5CF3,
dissociation energy of D(C6F5–Br), excitationenergies of excimers and rare gas atoms
reported in Refs. 22–29 for the calculations ofenergetics in each reaction. To be best of ourknowledge, D(C6F5CF2–F) and D(F–C6F4CF3)
values are unknown. The D(C6F5CF2–F) value
was estimated by using an average value
between D(CF3–F) and D(CF3CF2–F), whereas
the D(F–C6F4CF3) value was assumed to be thesame as that of D(F–C6F5).

3.

Results and Discussion

3.1 Branching ratios of RgX* and Rg* in the
Kr+/C6F5Br- and Xe+/C6F5Br- reactions
Figure 1(a) shows a typical emission
spectrum resulting from the Kr+/C6F5Brreaction. A strong Kr atomic line due to theKr(5s[3/2]→4p6 1S0) transition is observed at
124 nm. In addition, three transitions of KrBr*
excimer are observed in the 170–250 nm region.
(a)Kr*

KrBr(B-X)
KrBr(C-A)

KrBr(D-X)
150

120

x 10
250

200

280

Wavelength (nm)(5)

The partial pressures in the reaction zone were
1.0 Torr (1 Torr = 133.33 Pa) for He, 5–40
mTorr for Kr or Xe, and 3–5 mTorr for C6F5Br
and C6F5CF3. A small amount of Br- anions isformed by a dissociative electron attachment
to C6F5Br (4b). We previously found that thefollowing three-body recombination reaction

(6a)
(6b)

(b)

XeBr(B-X)

x2
150

200

250

280

Wavelength (nm)Fig. 1. Emission spectra resulting from the (a)Kr+/C6F5Br- and (b) Xe+/C6F5Br- reactions.

令和 5 年度

九州大学大学院総合理工学報告

KrBr* excimer bands consist of the strong
B(1/2)–X(1/2) transition in the 180–210 nm
region and the weak broad C(3/2)–A(3/2)
transition in the 210–250 nm region. The
D(1/2)–X(1/2) transition is observed as a very
weak shoulder band of the B–X transition in
the 170–190 nm region, The energetics for theformation of KrBr(B,C,D) from the Kr+/C6F5Brreaction is as follows:
Kr+ + C6F5Br→ KrBr(B) + C6F5 + 3.5 eV,→ KrBr(C) + C6F5 + 3.5 eV,→ KrBr(D) + C6F5 + 2.8 eV.

(7a)
(7b)
(7c)

All processes are highly exothermic, which
are energetically allowed.
Possible mechanisms for the formation ofKr(5s[3/2]1) atoms are direct neutralization (8a),neutralization involving radiative cascade fromhigher energy Kr* states (8b), andpredissociation of highly vibrationally excited
KrBr** states (8c).
Kr+ + C6F5Br→ Kr(5s[3/2]1) + C6F5Br + 2.8 eV,→ Kr* + C6F5Br,↓ hν (cascade)Kr(5s[3/2]1) + C6F5Br,→ KrBr** + C6F5,↓ (predissociation)
Kr(5s[3/2]1) + Br + C6F5 – 0.58 eV.

(8a)
(8b)
(8c)

Since predissociation process (8c) is endoergic,
this process is energetically excluded frompossible mechanisms at thermal energy (≈300
K). When emission spectrum in the 400–800
nm region was observed to examine thecontribution of the radiative cascade from theupper Kr* states to the Kr(5s[3/2]1) state (8b),no Kr* lines were observed. It was therefore
concluded that the contribution of process (8b)is negligible and that only direct neutralization
process (8a) is responsible for the formation ofKr(5s[3/2]1).
Based on above results, both recombination
reaction leading to KrBr(B,C,D) (7a)–(7c) andneutralization process (8a) occur competitively
in the Kr+/C6F5Br- reaction. The branchingratio of processes (7a)–(7c) and (8a) was
determined to be 0.14:0.86 by measuring thetotal intensities of KrBr* and Kr* emissions.
Figure 1(b) shows a typical emission
spectrum resulting from the Xe+/C6F5Brreaction in the 140–285 nm region. The B(1/2)–
X(1/2) transition of XeBr* with a long tail band

第 45 巻第1号

27

degrading to blue is identified in the 250–285
nm region. Although a Xe line due to theXe(6s[3/2]1→5p6 1S0) was observed at 147 nm in
the Xe+/C6F5Cl- reaction,16) it was not found in
the Xe+/C6F5Br- reaction. The energetics for theformation of XeBr(B) and Xe(6s[3/2]1) from the
Xe+/C6F5Br- reaction is as follows:
Xe+ + C6F5Br→ XeBr(B) + C6F5 + 3.2 eV,→ Xe(6s[3/2]1) + C6F5Br + 2.5 eV.

(9a)
(9b)

Both processes (9a) and (9b) are energeticallyallowed. On the basis of spectroscopic data, thebranching ratio of (9a):(9b) was found to be
1.00:0.00.
3.2 Branching ratios of RgX* and Rg* in the
Kr+/C6F5CF3- and Xe+/C6F5CF3- reactions
Figures 2(a) and 2(b) show emission spectraandresultingfrom
the
Kr+/C6F5CF3Xe+/C6F5CF3 reactions, respectively. A strongKr(5s[3/2]1→4p6 1S0) line is observed at 124 nm
in Fig. 2(a), whereas a strong Xe(6s[3/2]1→5p6
1S0) line is observed at 147 nm in Fig. 2(b).
PossibleformationmechanismsofKr(5s[3/2]1) and Xe(6s[3/2]1) atoms are direct
neutralization (10a) and (11a), neutralization
involving radiative cascade from higher energy
Kr* and Xe* states (10b) and (11b), andpredissociation of highly vibrationally excited
KrF** and XeF** states (10c), (10d), (11c), and(11d).
Kr+ + C6F5CF3→ Kr(5s[3/2]1) + C6F5CF3 + 3.1 eV, (10a)→ Kr* + C6F5CF3,↓ hν (cascade)(10b)
Kr(5s[3/2]1) + C6F5CF3,→ KrF** + C6F5CF2 or C6F4CF3,↓ (predissociation)
Kr(5s[3/2]1) + F + C6F5CF2 – 2.5 eV, (10c)Kr(5s[3/2]1) + F + C6F4CF3 – 1.9 eV. (10d)Xe+ + C6F5CF3→ Xe(6s[3/2]1) + C6F5CF3 + 2.8 eV, (11a)→ Xe* + C6F5CF3,↓ hν (cascade)(11b)
Xe(6s[3/2]1) + C6F5CF3,→ XeF** + C6F5CF2 or C6F4CF3,↓ (predissociation)Xe(6s[3/2]1) + F + C6F5CF2 – 2.8 eV, (11c)Xe(6s[3/2]1) + F + C6F4CF3 – 2.2 eV. (11d)Since predissociation processes (10c), (10d),Ion-ion recombination and neutralization reactions of Rg+ (Rg = Kr, Xe) with C6F5Br- and C6F5CF3- in the flowing afterglow

28

Kr+/C6F5CF3- and Xe+/C6F5CF3- reaction, eventhough they are energetically accessible.

(a)
Kr*
120

150

200

250

280

Wavelength (nm)

(b)
Xe*

150

200

250

280

Wavelength (nm)Fig. 2. Emission spectra resulting from the (a)Kr+/C6F5CF3- and (b) Xe+/C6F5CF3- reactions.
(11c), and (11d) are endoergic, they areenergetically
excludedfrompossiblemechanisms. In order to examine thecontribution of radiative cascade from upper
Kr* and Xe* states, processes (10b) and (11b),
emission spectra in the 280–800 nm region
were measured. The absence of Kr* and Xe*from upper states in the UV and visible region
show that these radiative cascade processes areunimportant. Thus, we concluded that direct
neutralization reactions (10a) and (11a) areresponsible for the formation of Kr(5s[3/2]1) andXe(6s[3/2]1).
It is known that KrF(B–X,D–X,C–A) andXeF(B–X,D–X,C–A) excimer emissions areobserved in the 150–400 and 200–450 nm
region, respectively.9,30,31) It should be notedthat KrF(B–X,D–X,C–A) and XeF(B–X,D–X,C–A) emissions were not observed in the

Kr+ + C6F5CF3→ KrF(B) + C6F5CF2 + 2.3 eV,→ KrF(B) + C6F4CF3 + 2.9 eV,→ KrF(C) + C6F5CF2 + 2.3 eV,→ KrF(C) + C6F4CF3 + 2.8 eV,→ KrF(D) + C6F5CF2 + 1.6 eV,→ KrF(D) + C6F4CF3 + 2.2 eV.

(12a)
(12b)
(12c)
(12d)
(12e)
(12f)

Xe+ + C6F5CF3→ XeF(B) + C6F5CF2 + 2.1 eV,→ XeF(B) + C6F4CF3 + 2.6 eV,→ XeF(C) + C6F5CF2 + 2.0 eV,→ XeF(C) + C6F4CF3 + 2.5 eV,→ XeF(D) + C6F5CF2 + 0.7 eV,→ XeF(D) + C6F4CF3 + 1.2 eV.

(13a)
(13b)
(13c)
(13d)
(13e)
(13f)

Thus, it was found that the branching ratios ofprocesses (12a–12f):(10a) and (13a–13f):(11a)are 0.00:1.00 for both reactions.
In Table 1 are summarized the branchingratios of RgX* excimers and Rg* atoms in thereactions of Kr+ and Xe+ with C6F5Br- andC6F5CF3-. For comparison, corresponding data
for C6F6- and C6F5Cl- are also given.11,16)
Although both Rg+(2P1/2) and Rg+(2P3/2)
components are formed by Penning ionization(2) and (3), the lower Rg+(2P3/2) state is
expected to be major component in the present
experiments as reported previously.16)

Table 1. Branching ratios of RgX* and Rg* in the reactions of Rg+ (Rg = Kr and Xe) with
C6F5X- (X=F, Cl, Br, and CF3).
Reaction
Kr /C6F6

KrF(B,C,D)-

Ref. 110.001

Ref. 160.00

Kr +/C6F5Br-

This work

0.00-

This work

0.00

+

-

Kr +/C6F5Cl

Kr /C6F5CF3+

Reaction
Xe+/C6F6-

Xe /C6F5Cl+

XeF(B,C,D)-

Ref. 11

0.00

Ref. 16

0.00

Xe+/C6F5Br-

This work-

This work

Xe /C6F5CF3+

KrCl(B,C,D)

KrBr(B,CD)

0.69
0.14

5s[3/2]1

5p[3/2]25p[5/2]3

0.000

0.454

0.545

0.31

0.00

0.00

0.86
1.00

XeCl(B,C,D)

XeBr(B,C,D)

0.89
1.00

0.00

Kr*

Xe*
6s[3/2]1

6p[1/2]0

0.00

1.00

0.11

0.00

0.00
1.00

令和 5 年度

九州大学大学院総合理工学報告

3.3 Reaction mechanisms for the formation of
RgX* and Rg* in the reactions of Rg+ with
C6F5Cl-, and C6F5CF3We reported that the electron affinity oftarget molecules and the dissociation energy ofC6F5–X leading to X- anion would be principal
factor in assessing the branching ratio of thetwo channels.11,16) The electron affinities of
C6F5X provide energies required for an electron
release from their anions.
C6F6- → C6F6 + e- – 0.53 eV,
C6F5Cl- → C6F5Cl + e- – 0.75 eV,
C6F5Br- → C6F5Br + e- – 1.15 eV,
C6F5CF3- → C6F5CF3 + e- – 0.86 eV.

(14)
(15)
(16)
(17)

On the other hand, the dissociation energies of
D(C6F5–X-), D(C6F5CF2–F-), and D(F-–C6F4CF3),
which are required for the formation of RgX*
excimers, are as follows.
C6F6- → C6F5 + F- – 2.16 eV,
C6F5Cl- → C6F5 + Cl- – 1.11 eV,
C6F5Br- → C6F5 + Br- – 1.19 eV,
C6F5CF3- → C6F5CF2 + F- – 3.05 eV,
C6F5CF3- → C6F4CF3 + F- – 2.49 eV.

(18)
(19)
(20)
(21a)
(21b)

Since the electron affinity of C6F5Br- is largest
among the four C6F5X reagents, an electrontransfer from C6F5X- to Rg+ is most unfavorable.
On the other hand, the D(C6F5–Br-) value issmaller than those of D(C6F5CF2–F-) and D(F-–C6F4CF3). Therefore, it is expected that excimer
formation via Br- transfer occurs for C6F5Br-.
Since the D(C6F5CF2–F-), and D(F-–C6F4CF3)
values are larger than those of other C6F5X
reagents, F- transfer is unfavorable for C6F5CF3-.
On the other hand, the electron affinity of
C6F5CF3 is smaller than that of C6F5Br.
Therefore, it is expected that neutralization
reaction via an electron transfer is favorable
exit channel for C6F5CF3-. These predictions are
consistent with the experimental observations
that excimer formation via Br- transfer occurs
for C6F5Br-, as in the case of C6F5Cl-,16) whereas
only neutralization reactions leading to low
lying Kr(5s[3/2]1) and Xe(6s[3/2]1) states takeplace for C6F5CF3-. It was thus confirmed thatelectron affinities of target molecules anddissociation energies of C6F5X- leading to Xplay a significant role in the ion–ion
recombination and neutralization reactions of
Rg+(Kr, Xe) with C6F5Br- and C6F5CF3-, as in
the cases of C6F6- and C6F5Cl-.11,16)

4.

第 45 巻第1号

29

Summary and Conclusion

The Kr+/C6F5Br-, Xe+/C6F5Br-, Kr+/C6F5CF3-,
ion–ionmutualand
Xe+/C6F5CF3recombination and neutralization reactions
have been spectroscopically studied in the He
flowing afterglow. The branching ratios ofrecombination and neutralization reactions
were found to be 0.14:0.86, 1.00:0.00, 0.00:1.00,
and 0.00:1.00 for the Kr+/C6F5Br-, Xe+/C6F5Br-,
Kr+/C6F5CF3-, and Xe+/C6F5CF3- reactions,
respectively. These results suggested that thebranching ratio between recombination
reaction leading to RgX* excimer andneutralization reaction leading to Rg* atoms
are different between C6F5Br- and C6F5CF3-.
Results showed that Br- transfer to form RgBr*
excimers occurs for C6F5Br-, whereas
neutralization leading to Rg* through anelectron transfer from C6F5CF3- to Rg+ is only
product channel for C6F5CF3-. It was concluded
that electron affinities of target molecules anddissociation energies of target molecular anions
leading to X- are important factors indetermining the branching ratio between therecombination and neutralization channels in
the ion–ion reactions of Rg+(Kr, Xe) with
C6F5Br- and C6F5CF3-, as in the cases of C6F6and C6F5Cl- reported previously.11,16)
Acknowledgments
The authors acknowledge Prof. Kenji Furuya
of Kyushu University for his careful reading of
our manuscript. This work has been supportedby the Morino Foundation for molecular science(1992), the Iwatani Naoji Memorial Foundation(1993), and Showa Shell Sekiyu Foundation forenvironmental research (1995).
References
1)
2)
3)
4)
5)
6)
7)

8)

J. R. Peterson, W. H. Aberth, J. T. Moseley, and J. R.
Sheridan, Phys. Rev. A 3, 1651 (1971).
J. T. Moseley, R. E. Olson, and J. R. Peterson, Case
Stud. At. Phys., 5, 1 (1975).
D. R. Bates, “Case Studies in Atomic Physics ”, Editedby E. W. McDaniel and M. R. C. McDowell, North
Holland, Amsterdam, Vol. 4, p. 57 (1974).
D. Smith and M. J. Church, Int. J. Mass Spectrom. lon
Phys., 19, 185 (1976).
M. J. Church and D. Smith, J. Phys. D, 11, 2199 (1978).
M. R. Flanney, Adv. Atomic, Mol. Opt. Phys., 32, 117(1994).
a) N. S. Shuman, T. M. Miller, R. Johnsen, and A. A.
Viggiano, J. Chem. Phys., 140, 044304 (2014). b) J. P.
Wiens, N. S. Shuman, T. M. Miller, and A. A. Viggiano,
J. Chem. Phys., 144, 204309 (2016).
M. Zauner-Wieczorek, J. Curtius, and A. Kürten,
Atmos. Chem. Phys., 22, 12443 (2022).

30
9)
10)
11)
12)
13)
14)
15)
16)
17)
18)
19)
20)
21)

Ion-ion recombination and neutralization reactions of Rg+ (Rg = Kr, Xe) with C6F5Br- and C6F5CF3- in the flowing afterglow
M. Tsuji, M. Furusawa, and Y. Nishimura, Chem.
Phys. Lett., 166, 363 (1990).
M. Tsuji, M. Furusawa, H. Kouno, and Y. Nishimura,
J. Chem. Phys., 94, 4291 (1991).
M. Tsuji, H. Ishimi, and Y. Nishimura, Chem. Lett.,
25, 515 (1996).
M. Tsuji, Trends Phys. Chem., 5, 25 (1995).
M. Tsuji, Houshasenkagaku, 62, 18 (1996).
M. Tsuji, M. Nakamura, and Y. Nishimura, Chem.
Lett., 26, 259 (1997).
M. Tsuji, M. Nakamura, Y. Nishimura, E. Oda, H.
Oota, and M. Hisano, J. Chem. Phys., 110, 2903 (1999).
M. Tsuji, H. Ishimi, K. Uto, and J.-I. Hayashi, Eng. Sci.
Rep., Kyushu Univ., 45, 7 (2023).
M. Tsuji, H. Ishimi, K. Uto, and J.-I. Hayashi, Eng. Sci.
Rep., Kyushu Univ., 45, 13 (2023).
A. L. Schmeltekopf and F. C. Fehsenfeld, J. Chem.
Phys., 53, 2000 (1970).
C. R. Herd, N. G. Adams, and D. Smith, Int. J. Mass
Spectrom. Ion Process., 87, 331 (1989).
F. J. Davis, R. N. Compton, and D. R. Nelson, J. Chem.
Phys., 59, 2324 (1973).
M. Tsuji, M. Ide, E. Oda, and Y. Nishimura, J. Chem.
Phys., 109, 3374 (1998).

22) C. E. Moore, “Atomic Energy Levels,” U.S. GPO,
Washington D.C., Natl. Bur. Stand. (U.S.) Circ. 467(1949).
23) Atomic Spectra Database, NIST Standard Reference
Database, 78, Ver. 5.9. Oct. (2021).
24) Y.-R. Luo, “Bond Dissociation Energies”, in CRC
Handbook of Chemistry and Physics, 81th Ed., CRC
Press, Boca Raton (2000).
25) NIST Chemistry WebBook, NIST Standard Reference
Number69(2023)
Database,https://doi.org/10.18434/T4D303.
26) T. H. Dunning and P. J. Hay, J. Chem. Phys., 69, 134(1978).
27) P. J. Hay and T. H. Dunning, J. Chem. Phys., 69, 2209
(1978).
28) M. T. Jones, T. D. Dreiling, D. W. Setser, and R. N.
McDonald, J. Phys. Chem., 89, 4501 (1985).
29) E. J. D. Vredenbregt, M. P. M. van Besouw, M. J. J.
Vrakking, M. J. Mietus, C. E. P. Gerrits, and H. C. W.
Beijerinck, J. Chem. Phys., 98, 7903 (1993).
30) D. Zhong, D. W. Setser, R. Sobczynski, and W.
Gadomski, J. Chem. Phys., 105, 5020 (1996).
31) D. Zhong and D. W. Setser, Chem. Phys. Lett., 207,555 (1993)．