Chenxi Zhu, H. Kjaergaard, B. Henry
Jul 15, 1997
Citations
1
Influential Citations
22
Citations
Journal
Journal of Chemical Physics
Abstract
Vapor phase overtone spectra of 2,6-difluorotoluene are recorded in the ΔvCH=2 and 3 regions by conventional near-infrared spectroscopy and in the ΔvCH=4–6 regions by intracavity dye/titanium: sapphire laser photoacoustic spectroscopy. The spectra are interpreted on the basis of ab initio calculations at the HF/6-31G* level. The methyl regions of the spectra are complex due to coupling between the nearly freely rotating methyl rotor and CH stretching. A model has been developed to predict the methyl spectral profiles, which uses the harmonically coupled anharmonic oscillator local mode model and the rigid rotor model for stretching and torsion, respectively. A dipole moment function is formulated which combines a Taylor series for CH stretching and a Fourier series for torsion. The dipole moment function includes both angular dependence and higher order expansion terms in the CH-stretching coordinate. The model is successful in predicting the methyl overtone spectral profiles and attributes these profiles...