PRERESONANCE RAMAN EFFECT ON THE OD STRETCHING RAMAN-SPECTRA OF METHANOLIC LIX SOLUTIONS (X = CL, BR AND I)

Intensities of the OD stretching modes in the Raman spectra of LiX solutions (X = Cl, Br and I) in CH3OD were measured. It is shown that the intensities increase significantly with increasing halide concentration owing to a pre-resonance Raman effect arising from charge-transfer states of hydrogen bonds between halide ions and their solvated methanol molecules. The small dissociation of dissolved LiI molecules is the reason why no enhancement of the intensity is observed in the Raman OD stretching spectrum for a glassy methanolic LiI solution.