Spectroscopic studies on the liquid phase dynamics and interactions of acetonitrile

Abstract

Spectroscopic studies on the liquid phase dynamics and Interactions of acetonitrile. Microwave and far-infrared spectra were used to study the angular motion of CH(_3)CN molecules in the pure liquid and in the non-polar solvents carbon tetrachloride, benzene and n-heptane. The spectral data were analysed to give information on the static angular structure of the liquid and the rates of reorlentational motion of the CH(_3)CN molecules. The use of these two experimental techniques enabled the short and long time parts of the angular motion to be studied together using Fourier transform analysis of the combined microwave/far-Infrared spectrum. Band moment analysis was performed on the microwave/far-infrared band In order to obtain Information on Intermolecular torques. Gordon's sum rule was applied to the spectra In an attempt to estimate what proportion of the band is due to the presence of collision Induced dipoles In the CH(_3)CN molecules. The reorientational relaxation rates and static angular correlation factors obtained from the microwave/far-infrared spectra were compared with literature data on similar solutions obtained by depolarised light scattering experiments. The model for reorientational motion developed by Evans on the Mori formalism was fitted to the experimental spectrum of the pure liquid and the results discussed in terms of the parameters of the model. The V(_1) vibrational band of CH(_3)CN was analysed when the molecule was subject to hydrogen bonding' Interactions with methanol. An attempt was made to elucidate the processes which cause the vibrational band to be broadened in these solutions. The vibrational line shapes were analysed using the Kubo line shape theory for the rapid modulation limit.