The Raman band profiles of two vibrational bands of benzonitrile belonging to the a1 species (2243 and 1000 cm-1) were analysed by separating the isotropic and anisotropic components. Spectra of benzonitrile were recorded, using argon laser excitation, in solutions of CC14, CS2, cyclohexane, cyclohexanol and tertiary butyl alcohol-all having different viscosities. The rotational correlation times were evaluated from the band profiles. The results indicate that (a) the isotropic (and not the anisotropic) linewidth increases with increasing viscosity, which is attributed to the greater effect of intermolecular interactions on vibrational relaxation; and (b) the two modes of the same species give different relaxation times.
Volume 134, 2022
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