# ROTOR-VIBRATOR COUPLING EFFECTS IN METHYL CH STRETCHING OVERTONE SPECTRA OF GASEOUS TOLUENE

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 Title: ROTOR-VIBRATOR COUPLING EFFECTS IN METHYL CH STRETCHING OVERTONE SPECTRA OF GASEOUS TOLUENE Creators: Cavagnat, D.; Lespade, L.; Lapouge, C. Issue Date: 1998 Publisher: Ohio State University Abstract: The methyl CH stretching overtone spectra of toluene and of its deuterated derivatives $(C_{6}D_{5}CH_{3}, C_{6}D_{5}CH_{2}D$ and $C_{6}D_{5}CHD_{2})$ have been recorded by FTIR ($\Delta v=1$ to 4) and by intracavity dye laser photoacoustic spectrometry ($\Delta v=5$ and 6) at low resolution (0.5 to $2 cm^{-1}$). The different couplings likely to affect these spectra (anharmonic coupling of the vCH mode with the methyl group internal rotation. Fermi resonance coupling with combination states involving CH stretch/methyl bending modes) are considered. The parameters used to model these couplings are determined partly from ab-initio $calculations^{a}$, partly from fitting simultaneously the spectra of the different isotopic compounds. A preliminary analysis of the obtained results is presented. An attempt to compare them with those determined from the study of the corresponding overtone spectra of $nitromethane^{b}$ (which presents a similar hindering barrier to the methyl group rotation) is made in order to check the effect of the molecular environment of the methyl group on IVR phenomena. Description: $^{a}$ C. Lapouge and D. Cavagnat, J. Phys. Chem., to be published $^{b}$ D. Cavagnat and L. Lespade, J. Chem. Phys. 106, 7946, (1997) Author Institution: LPCM, Universit\'{e} Bordeaux I URI: http://hdl.handle.net/1811/19109 Other Identifiers: 1998-TI-13