Low-lying electronic states of SF2 and its ions as studied by the MRCI technique

Czernek, Jiřı́; Živný, Oldřich

doi:10.1016/j.chemphys.2007.12.009

Cited by 9 publications

(6 citation statements)

References 23 publications

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“…However, experimental data are available for the singlet excited states due in part to the fact that these states have spin-allowed transitions to and from the ground state with favorable oscillator strengths. There have been numerous previous theoretical studies on the low-lying singlet states of SF 2 , − and our results are generally in good agreement with these studies. The wave functions of the excited singlet and triplet electronic states, which exhibit recoupled pair bonding, have B 1 and A 2 spatial symmetry in the C 2 v point group.…”

Section: Resultssupporting

confidence: 92%

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Theoretical Studies of the Excited Doublet States of SF and SCl and Singlet States of SF₂, SFCl, and SCl₂

Leiding

Dunning

2012

J. Phys. Chem. A

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In previous work, we reported that the lowest-lying excited states of SF, SCl, SF(2), SFCl, and SCl(2) have recoupled pair bonds. In this study, we examine the analogous low-spin states--the (2)Σ(-) and (2)Δ states of SF and SCl and the excited singlet states of SF(2), SCl(2), and SFCl--which also possess recoupled pair bonds. In contrast to the excited states treated previously, the states studied in the present work have the same spin multiplicities as their respective ground states and are thus potentially observable via electronic excitation. Of particular interest are the minima on the (1)A″ potential energy surface of SFCl corresponding to bond-stretch isomers analogous to those found on the (3)A″ surface. In addition, we discovered that the first two excited states ((1)A″) accessible via vertical excitations from the ground state of SFCl have the electronic structure of the bond-stretch isomers. Thus, electronic excitation spectroscopic studies of SFCl could reveal a signature of the bond-stretch isomers. We will also present limited data on the lowest singlet Rydberg states of the triatomic species. Calculations were performed at the MRCI+Q/aug-cc-pV(Q+d,5+d)Z levels of theory.

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Section: Resultssupporting

confidence: 92%

“…There are several other previous calculations on the 4s Rydberg state (2 1 B 1 ) of SF 2 at varying levels of theory. − There is no experimental value of f e or T v to compare to our MRCI+Q/AVQZ + X 1 A 1 →2 1 B 1 values of SF 2 . Our SCl 2 T v for the Rydberg state differs by about 3 kcal/mol from the most recent experimental study.…”

Section: Resultsmentioning

confidence: 89%

Theoretical Studies of the Excited Doublet States of SF and SCl and Singlet States of SF₂, SFCl, and SCl₂

Leiding

Dunning

2012

J. Phys. Chem. A

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“…The geometries of the investigated electronic states were obtained using the procedure we described in detail in [3] and only briefly summarize here. The implementation of the MRCI approach [5], [6] was combined with the standard aug-cc-pVQZ basis set [7] (240 basis functions).…”

Section: Methodsmentioning

confidence: 99%

“…We devised a computational protocol that combines the multiconfigurational-reference internally-contracted configuration interaction (MRCI) [2] technique with extrapolations of the energies to the complete basis set (CBS) limit, and is capable of a highly accurate description of valence electronic states of both neutral and charged species [3]. Most recently we applied this approach to obtain the bond lengths r e , bond angles and adiabatic excitation energies T e of NF 2 , NF þ 2 and NF À 2 [4] to facilitate the modeling of the NF 3 plasma.…”

Section: Introductionmentioning

confidence: 99%

An MRCI investigation of the electronically excited states of difluorocarbene and its monovalent ions

Czernek

Živný

2008

Molecular Physics

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The MRCI/CBS computational protocol was employed to describe the low-lying electronic states of CF 2 in excellent agreement with experiment. Also of interest for modeling the fluorocarbon plasmas are the difluorocarbene ions, and the geometries, adiabatic excitation energies and orbital characteristics of their electronically excited states were established. Most of the transitions leading to the excited states were found to be monoelectronic and, for the dipole-allowed ones, the oscillator strengths and radiative lifetimes were predicted to aid in the spectroscopic studies.

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“…3 When compared with its neutral counterpart, the cationic SF 2 + species is, however, still far from being well characterized, with only a few computational [4][5][6][7] and only one prior experimental 8 study. The only experimental study available for the low-lying excited states of SF 2 + comes from the He I photoelectron ͑PE͒ spectrum, which was reported by de Leeuw et al 8 three decades ago.…”

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confidence: 98%

On the photofragmentation of SF2+: Experimental evidence for a predissociation channel

Zhang

Mao

Chen

2008

The Journal of Chemical Physics

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In light of its potential importance in the semiconductor industry, the SF 2 reactive intermediate has recently received increased attention from both experimentalists 1,2 and computational chemists. 3 When compared with its neutral counterpart, the cationic SF 2 + species is, however, still far from being well characterized, with only a few computational 4-7 and only one prior experimental 8 study. The only experimental study available for the low-lying excited states of SF 2 + comes from the He I photoelectron ͑PE͒ spectrum, which was reported by de Leeuw et al. 8 three decades ago. The spectral features observed in the PE spectrum were assigned to ionizations from the X 1 A 1 ground state of SF 2 to the X 2 B 1 ground state and five low-lying excited states ͑Ã 2 A 1 , B 2 B 2 , C 2 B 2 , D 2 A 1 , and Ẽ 2 A 2 ͒ of SF 2 + . 8 A recent ab initio study employing the high-level RCCSD͑T͒ method was carried out by Lee et al. 6 to calculate the potential energy functions ͑PEFs͒ for the X 1 A 1 state of SF 2 and for the six states of SF 2 + listed above. Since the experimental research regarding SF 2 + has lagged far behind, any useful information on the lowlying states of SF 2 + from the experimental side is highly desirable. 6 In this letter, we report the first observation on the photofragmentation dynamics of SF 2 + by recording the resonance-enhanced multiphoton ionization ͑REMPI͒ spectra of SF 2 and its concomitant SF + fragment, from which a predissociation channel occurring in the low-lying excited states of SF 2 + is revealed to account for the observed fragmentation. In the present experiment, SF 2 molecules in their ground state were produced by the pulsed dc discharge in a pulsed molecular beam of SF 6 ͑30% in Ar͒. Details of the experimental apparatus and procedure can be found in our previous publications. 9,2 The upper part of Fig. 1 shows the ͑2+1͒ REMPI excitation spectrum of 32 SF 2 ͑m / z =70͒ in the laser wavelength range of 293-325 nm. Based on previous work, 9,10 we can readily assign this spectrum to the Ẽ ͑4p͒ ← ←X 1 A 1 and F ͑4p͒ ← ←X 1 A 1 transitions of SF 2 . ͑See Ref. 9 for details regarding the assignments given in Fig. 1.͒ The lower part of Fig. 1 shows the simultaneously recorded REMPI "daughter" spectrum of 32 SF + ͑m / z =51͒. Notably, it is only from a certain onset wavelength of ϳ310.9 nm that this daughter spectrum resembles its "parent" one. Such type of spectral resemblance usually implies that a mechanism of REMPI followed by dissociation ͑REMPID͒ takes effect. 2,[9][10][11] To facilitate the following discussions, we put all relevant elements in an energy level diagram ͑Fig. 2͒. The horizontal dotted lines in Fig. 2 denote the adiabatic ionization energies ͑AIEs͒ for the six cationic states. 8,6 The threephoton energies used in our experiment lie Ͼ1.5 eV below the cationic dissociation limit ͑SF + ͑X 3 ⌺ − ͒ +F͑ 2 P 0 ͒͒, hence it is natural to consider only the four-photon excitation, i.e., a ͑2+2͒ REMPID scheme is most likely to account for the observed fragmentation. Care ...

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Low-lying electronic states of SF2 and its ions as studied by the MRCI technique

Cited by 9 publications

References 23 publications

Theoretical Studies of the Excited Doublet States of SF and SCl and Singlet States of SF₂, SFCl, and SCl₂

Theoretical Studies of the Excited Doublet States of SF and SCl and Singlet States of SF₂, SFCl, and SCl₂

An MRCI investigation of the electronically excited states of difluorocarbene and its monovalent ions

On the photofragmentation of SF2+: Experimental evidence for a predissociation channel

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Low-lying electronic states of SF2 and its ions as studied by the MRCI technique

Cited by 9 publications

References 23 publications

Theoretical Studies of the Excited Doublet States of SF and SCl and Singlet States of SF2, SFCl, and SCl2

Theoretical Studies of the Excited Doublet States of SF and SCl and Singlet States of SF2, SFCl, and SCl2

An MRCI investigation of the electronically excited states of difluorocarbene and its monovalent ions

On the photofragmentation of SF2+: Experimental evidence for a predissociation channel

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Theoretical Studies of the Excited Doublet States of SF and SCl and Singlet States of SF₂, SFCl, and SCl₂

Theoretical Studies of the Excited Doublet States of SF and SCl and Singlet States of SF₂, SFCl, and SCl₂