Picosecond Lifetimes and Efficient Decay Channels of Vibrational Models of Polyatomic Molecules in Liquids

Abstract

Convincing evidence is presented that anharmonic coupling between fundamental vibrational modes and overtones or combination modes is of major importance for the lifetime of vibrational states. The selection rules known to hold for Fermi resonance determine the decay channels. In a number of examples the decay pathways of vibrational energy were observed experimentally by measuring the population and depopulation of subsequent vibrations. Drastic variations of vibrational lifetimes were found for different vibrations of the same molecule.