MOLECULAR VIBRATIONAL-ENERGY FLOW - BEYOND THE GOLDEN-RULE

This article reviews some recent work in molecular vibrational energy flow (IVR), with emphasis on our own computational and experimental st udies. We consider the problem in various representations, and use the se to develop a family of simple models which combine specific molecul ar properties (e.g. size, vibrational frequencies) with statistical pr operties of the potential energy surface and wavefunctions. This marri age of molecular detail and statistical simplification captures trends of IVR mechanisms and survival probabilities beyond the abilities of purely statistical models or the computational limitations of full ab initio approaches. Of particular interest is IVR in the intermediate t ime regime, where heavy-atom skeletal modes take over the IVR process from hydrogenic motions even upon X-H bond excitation. Experiments and calculations on prototype heavy-atom systems show that intermediate t ime IVR differs in many aspects from the early stages of hydrogenic mo de IVR. As a result, IVR can be coherently frozen, with potential appl ications to selective chemistry.