Crossing of Anisotropic and Isotropic Raman Components in the Intermolecular Resonance Coupling of Vibrations. IV-Methanol Solutions in Acetone

Changes in the wavenumbers of the anisotropic and isotropic components of the O–H and C–O stretching bands of methanol in the Raman spectrum of methanolic solutions in acetone were investigated. Non‐coincidence values (defined as Δν=νaniso‐νiso) in the case of the O–H band changed with dilution by acetone from +85 cm−1 in pure methanol to ‐26 cm−1 in the most dilute solution, whereas the negative non‐coincidence ‐5 cm−1 of the C–O band of methanol remained almost unchanged with dilution by acetone. The unusual behaviour of the methanolic vibrations was explained by a third‐body mediation mechanism.