Dynamics of confined methyl iodide studied by Raman spectroscopy

Abstract

Raman spectroscopy was used to study the vibrational and reorientational dynamics of bulk and confined liquid methyl iodide. A set of five porous silica glasses with pore radii ranging from 15 to 38 Å was employed as the confining material. With decreasing pore size a decrease in the ν3 (C– I) vibrational correlation time and an increase in the molecular reorientational correlation time were found. It is noted that the two‐state fast‐exchange model is not applicable in Raman studies owing to slow diffusion of pore molecules compared with the Raman spectroscopic time‐scale. A phenomenological linear correlation between the correlation times and the reciprocal of the pore radius was found to be useful and employed for data analysis. A relatively low sensitivity of the reorientational dynamics of methyl iodide to confinement was explained by considering the shape and mass distribution of a methyl iodide molecule. Copyright © 2000 John Wiley & Sons, Ltd.

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