The 12B1, 12B2, 12A1, 12A2, 32A′(22B2), and 22A1 states of the 1,1-difluoromethane ion studied using multiconfiguration second-order perturbation theory

Xi, Hongwei; Huang, Ming‐Bao

doi:10.1016/j.cplett.2006.09.006

Cited by 11 publications

(2 citation statements)

References 26 publications

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“…This has widely been recognized as a composite band containing contributions from three ionic states (A, B, and C). 6 The present AIE study of the symmetry sequence gives 2 B 2 < 2 A 1 < 2 A 2 , in agreement with the studies of Tuckett et al, 8 Takeshita, 19 and Xi and Huang 20 (after allowing for interchange of B 1 and B 2 symmetry axes). The most intense contributions to the theoretical FC profiles are listed in Tables IV-VI.…”

Section: Band II Of the Pessupporting

confidence: 91%

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The ionic states of difluoromethane: A reappraisal of the low energy photoelectron spectrum including ab initio configuration interaction computations

Palmer

Biczysko

Baiardi

et al. 2017

The Journal of Chemical Physics

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A new synchrotron-based study of the photoelectron spectrum (PES) of difluoromethane is interpreted by an ab initio analysis of the ionic states, which includes Franck-Condon (FC) factors. Double differentiation of the spectrum leads to significant spectral sharpening; the vibrational structure observed is now measured with greater accuracy than in previous studies. Several electronic structure methods are used, including equation of motion coupled cluster calculations with single and double excitations (EOM-CCSD), its ionization potential variant EOM-IP-CCSD, 4th order Møller-Plesset perturbation theory (MP4SDQ) configuration interaction (CI), and complete active space self-consistent-field (CASSCF) methods. The adiabatic ionization energies (AIEs) confirm the assignments as band I, one state 1B (12.671 eV); band II, three states, 1B (14.259) < 1A (15.030) < 1A (15.478 eV); and band III, three states, 2B (18.055) < 2A (18.257) < 2B (18.808 eV). The three ionizations in each of the bands II and III lead to selective line broadening of the PES structure, which is attributed to vibronic overlap. The apparent lack of a vibrational structure attributable to both the 1A and 2A states in the PES arises from line broadening with the preceding states 1B and 2B, respectively. Although these A states clearly overlap with their adjacent higher IE, some vibrational structure is observed on the higher IE. The effects of vibronic coupling are evident since the observed structure does not fit closely with the calculated Born-Oppenheimer FC profiles. Correlation of the lowest group of four AIEs in the PES of other members of the CHX group, where X = F, Cl, Br, and I, clearly indicate these effects are more general.

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Section: Band II Of the Pessupporting

confidence: 91%

“…4 Most early spectral PES results and assignments [12][13][14] for CH 2 F 2 have been superseded, enabling us to concentrate on recent studies. 4,8 Electron impact (EI) [15][16][17][18] and theoretical methods 19,20 are sources where additional information can also be found.…”

Section: Introductionmentioning

confidence: 99%