Rotational dynamics in liquid acetonitrile. Temperature and concentration effects in the non-ideal CH3CN/CCl4 mixture

Abstract

The effect of both temperature and dilution on the orientational relaxation rate of acetonitrile has been considered. The half bandwidths obtained by Raman scattering and infrared absorption techniques were corrected considering the effective temperature of the scattering volume in the Raman, and the thermostatic temperature in the IR experiments. This procedure, adopted for the first time in studies of dynamical processes, has shown the presence of two different dynamic regimes in the CH₃CN/CCl₄ solutions, due to the low-boiling azeotropic mixture. The results obtained have been discussed within the framework of the rotational diffusion theory. Experimental values of the molecular and hydrodynamic volumes of acetonitrile were compared with the respective theoretical values.