High-resolution FTIR measurement of the 2ν8 band of methylene fluoride (CH2F2)

Singh, P.; Deo, M. N.; Kawaguchi, Kentarou

doi:10.1016/j.jms.2005.08.015

Cited by 5 publications

(1 citation statement)

References 23 publications

(41 reference statements)

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“…Several high-resolution Fourier transform infrared (FTIR) spectral studies have been reported. [43][44][45][46] However, several of the IR bands analyzed show perturbations through Coriolis and other interactions; our theoretical harmonic values do not include such interactions. The analyses used for comparisons between theory and experiment in the X 1 A 1 state are given in Table II.…”

Section: A General Aspectsmentioning

confidence: 90%

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: A General Aspectsmentioning

confidence: 90%