Under this project, funded by the Chemical Structure, Dynamics and Mechanisms - A (CSDM-A) Program of the Chemistry Division, Professor Richard Mabbs of Washington University in St. Louis is studying what happens when molecules collide with electrons and temporarily capture them. The Mabbs research group is particularly interested in how molecules vibrate and rotate during the electron capture process. The results are particularly important for a full understanding of the electron transfer/collision induced chemistry which occurs in areas as diverse as chemical reactions, catalysis, radiation damage in DNA, remediation strategies for removing volatile organic air pollutants, and ionospheric chemistry. This project serves as a vehicle for the education and training of graduate students and undergraduate students who are directly involved in the research. Professor Mabbs integrates some of the results of the research into his formal chemistry courses.
Metastable, excited electronic states of anions represent free electrons interacting strongly with a neutral molecule. This project probes vibronic coupling within such states using high resolution velocity mapped photoelectron imaging and tunable photoexcitation. Vibrationally resolved photodetachment spectra of small molecular anions are recorded. Excitation to individual (ro)vibrational levels of a metastable excited anion state is followed by electron loss via one of the (ro)vibrational levels of the neutral molecule. The photon energy dependence of a vibrational channel cross section represents an action spectrum for autodetachment from a (ro)vibronic state of the excited anion, revealing which vibrational levels are strongly coupled in the anion. The action spectra also yield the energies of internal states of the excited anion and therefore provide valuable benchmarks for state-of-the art calculations of highly correlated and open shell, excess electron species.