Edward Grant of Purdue University is supported by the Experimental Physical Chemistry Program to continue his research on state-to-state photoionization and dynamics of intramolecular relaxation in highly excited states of small molecules. The main objective of this work is to accumulate, for a number of polyatomic systems, state-detailed spectroscopic information of sufficient resolution to support full-scale Multichannel Quantum Defect Theory calculations. Systems to be studied include hydrocarbon and metal-centered free radicals that form closed-shell cations. The PI will use multiresonant excitation techniques to make high-resolution spectroscopic measurements of resonant lineshapes and energies associated with transitions to states which are coupled to ionization and dissociation continua, and photoselection with specialized detection methods to study rovibrational structure in the electronic ground states of cations and precursor free radicals. The effort to describe energy flow in isolated molecules has added considerably to our understanding of chemical reactivity, and served for many years as an important focus of research in chemical physics. The study of intramolecular relaxation remains today a vital point of contact between experimental and theoretical molecular dynamics. Particularly important is the transfer of energy between electronic and internuclear degrees of freedom. The detailed dynamics of such processes can give rise to significant chemical consequences. For example, issues associated with the dynamics of energy transfer between electronic coordinates and internuclear ones underlie contemporary efforts to direct the outcomes of chemical transformations.
