Study op V-V transfer in polyatomic molecules by laser-induced fluorescence and ultrasonic absorption measurements

Abstract

Slow vibrational energy transfer between the two lowest modes of such polyatomic molecules is studied, where the second lowest mode lies above the overtone of the lowest mode. The results of ultrasonic absorption and laser-induced fluorescence experiments in methylene halides are discussed. These results and additional data taken from the literature are correlated. The conditions for inefficient energy exchange between the two lowest modes of molecules are explored. The most important channel at 300 K is probably not energy transfer to the overtone as found by SSH-type calculations, but direct energy exchange between the two fundamentals despite the larger energy gap.