High resolution FTIR spectrum of vinyl fluoride near 9 μm: rovibrational analysis of the v ₇ band

Abstract

The Fourier transform infrared spectrum of CH2--~-CHF has been investigated in the v7 band region around 115 5 cm -1 at a resolution of about 0"002 cm-1. This fundamental of symmetry species A' yields an a/b hybrid band with a prevalent contribution of the a-type component. The band is affected by first-order b-Coriolis resonance with the v9 + v12 combination, and the interactions are markedly stronger for the K'a = 11 and 12 levels; local perturbations with crossings due to higher-order a-and b-Coriolis resonances have also been observed. The rovibrational analysis led to the identification of more than 2900 lines of v7 with J ~< 64 and Ka ~< 18, while no features were detected for the v9 + v12 band. Using Watson's A-reduction Hamiltonian in the I" representation, the present ground state combination differences combined with available microwave data led to improved sextic distortion terms for the ground state. Of the assigned lines, 2329 free of major resonance contribution provided excited state constants for the v 7 band. Furthermore, from the perturbation effects near the crossings, some parameters for the v 9 + v12 combination have been determined.

Toward a Complete Understanding of the Vinyl Fluoride Spectrum in the Atmospheric Region

“…The spectrum around 8.7 mm is characterized by the ro-vibrational absorptions belonging to the n 7 normal mode which corresponds to the CÀF stretching vibration. The spectral structure was originally assigned by Stoppa et al, [21] although the observed irregularities, ascribed to a/b-type Coriolis couplings with the neighbouring n 9 + n 12 vibrational state, were described only qualitatively. Herein, this perturbation, which mainly affects rovibrational states with K a !…”

“…Ground state [21] n 7 = 1 n 9 = n 12 = 1 showing the uneven line spacing caused by the Coriolis coupling of vibrational states n 7 = 1 and n 9 = n 12 = 1. Lower trace: FTIR spectrum; Upper trace: theoretical spectrum computed using the data of Table 1 and the obtained transition dipole moments.…”

“…Obtained Hamiltonian constants [cm À1 ] for the n 7 = 1 and n 9 = n 12 = 1 vibrational coupled levels of CH 2 CHF. [a] Ground state [21] n 7 = 1 n 9 = n 12 = 1 n 0 1155.20204 8 (7 6 D J 10 6 0.28126(8) 0.27809 5 ( 7 7 ) [b] D JK 10 5 À0.2537(2) À0.2539 0 (1 2 ) D K 10 4 0.4436 7 (1 7 ) 0.47348 2 (6 6 ) d J 10 7 0.5891(1) 0.5895 8 (4 7 ) d K 10 5 0.1186(1) 0.1355 9 (5 8 )…”

Infrared measurements and rovibrational study of the v7 band of vinyl chloride by diode laser spectroscopy

“…Di culties in identifying the weak lines of the 37 Cl isotopomer in badly overlapped regions have been overcome by resorting to the spectra of pure monoisotopic 37 Cl species. This study is part of a more extensive investigation in our laboratory of the spectroscopic characteristics of di erent halogenated compounds [11,12].…”

High-Resolution Infrared Study of Vinyl Fluoride in the 750−1050 cm-1 Region: Rovibrational Analysis and Resonances Involving the ν8, ν10, and ν11 Fundamentals

“…11 Ground-state constants were determined many years ago from microwave spectra 12,13 and more recently using microwave data available in the literature together with infrared combination differences coming from the ν 7 fundamental. 14 The present work deals with the interpretation of the rovibrational structure of the ν 8 , ν 10 , and ν 11 bands of vinyl fluoride in the region between 750 and 1050 cm -1 where highresolution spectra have been investigated for the first time. The determination of the spectroscopic parameters of these fundamentals are also of considerable interest, since the related absorptions fall in the range of atmospheric windows for the detection of trace gases.…”