Intramolecular Dynamics from Eigenstate-resolved Infrared Spectra

Understanding intramolecular energy flow in molecules is one of the central goals of chemical physics. Statistical theories [such as Rice-Ramsperger-Kassel-MarCus (RRKM) theory] of unimolecular reaction rates, which assume that the vibrational degrees of freedom rapidly exchange energy, have proved extremely successful (1). Recent work on small molecules has provided rigorous tests of these theories (2). With the success of unimolecular reaction theory, it has become clear that intramolecular vibrational energy redistribution (IVR)’is a nearly universal phenomenon when molecules have enough energy to break bonds. However, despite this success, several important issues about the na’t, ure ~3f the assumed statistical rnotion have been left .unresolved. Definifiw; measurements of the time scale of the IVR process have only recently.become possible. Unimolecular reaction theories only require IVR to be faster than the dissociation rate. For most chemical reactions, these