Study of the ν1-ν3 infrared hot band of CH3Cl35

Abstract

The study of the ν1-ν3 hot band has been performed with very high resolution; the parameter αA 3 and the centrifugal distortion constants of the state v3 = 1 have been measured, and the values, already known, of αB 3 and ν03 have been confirmed

Anharmonic resonances between the upper rovibrational levels of the and infrared bands of CH335Cl studied in a high-resolution FTIR spectrum from 4250 to 4600 cm-1

“…As in [1,2], it has been possible to assign the J values of the lines and, whenever they were greater than 2, the K values of the sub-bands, using the combination differences relationships since B", D~ and D~x of the vibrational ground state are well known [11].…”

“…in the present case, analogously between v 2 + v4 ~ 1 and both components of v 4 + v5), several anharmonic resonances were revealed. First, there is the well-known anharmonic resonance between v~ ~ and 3v~ 1 [4][5][6][7][8][9], which obviously occurs between v 2 + v~ 1 and v 2 + 3v6 ~ [1,2] and also between v~ ~ + v~ 1 and v~ 1 + 3v6 9 ~ [2], but surprisingly with coupling constants more different than expected (2.6 and 3.5cm -~ respectively). It was then apparent that a further anharmonic interaction between v2 + v~ ~ and a different band, which was identified as v~ + v~ 1 (the coupling constant being around 3.2 cm-~), is involved.…”

“…For two of the three sub-bands not considered in the calculation, the difference between observed and calculated wavenumbers is small (0.2 cm-1); for the last one, it is much larger (1-18 cm-1), and this is probably caused by the upper level of 2v 3 + 3v~ 1, which has not been taken into account in the present model, because of the lack of information related to this band. The 4300-4450cm -~ [1] and the 4250-4600cm -l [2]~f ranges of the infrared spectrum of methyl chloride CH3C1 have already been studied. Although, as in any methyl halide [3], the most prominent feature of the spectrum is the strong x-y Coriolis resonance between the v 2 and v5 modes (i.e.…”

“…Both studies [1,2] employed the same spectrum, which had been recorded by one of us (G. G.) on a high-information Fourier-transform interferometer [10] with an absorption path length of 28m and a pressure of 106Pa of natural methyl chloride.…”