Ultrafast Mode-Specific Intermolecular Vibrational Energy Transfer to LiquidNitromethane

摘要

Understanding the vibrational dynamics of polyatomic molecules in polyatomic solutions is central to many problems in chemistry, physics, and biology. Despite extensive experimental and theoretical investigations, one problem has received very little attention, namely, intermolecular vibrational energy transfer between two different polyatomic molecules in solution. The conventional methods of optical line shape analysis can provide information about vibrational dephasing and vibrational relaxation (in liquid state dynamics, vibrational relaxation is ordinarily used to denote pure phase relaxation processes), but rarely does the optical line shape provide any information about vibrational energy relaxation processes. There are many different types of energy relaxation processes, and to eliminate confusion, we will use the following consistent set of definitions: VER = vibrational energy relaxation; VC = vibrational cooling, the loss of energy from a vibrationally hot molecule to the surroundings generally occurring through several VER steps; and IVET = intermolecular vibrational energy transfer, the transfer of vibrational energy between identical or different molecules in a condensed matter sample. jg p2.