This award will support a two-year cooperative research project in physical chemistry between Professor Mark A. Johnson of Yale University and Professor Tamotsu Kondow of the University of Tokyo. They will collaborate on research into "Chemical Reactions of Microclusters in Gas Phase and Interaction with Surfaces." Over the past five years, physical chemists have become increasingly interested in molecular clusters as a tool to learn about the molecular aspects of condensed phase behavior. Professor Johnson's group at Yale has developed methods based on mass spectrometry to isolate a specific number of solvent molecules around a solute molecule or reaction complex in order to study the size dependence of bimolecular and photo-initiated chemical processes. A particularly interesting solute "anion" is the free electron itself, which has been studied through the accommodation of an excess charge by a collection of closed shell species. The behavior of excess charges in polar media is of primary interest in radiation chemistry and is presently a focal point for experimental tests of current theories. In previous work, the Yale group has discovered that several homogeneous systems possess strong absorptions near the binding energy of the excess electron, and that the excitation of these absorptions leads to fragmentation of the cluster rather than ejection of the electron. Excitation near the binding energy means that the ejected electron would have very low kinetic energy and apparently cannot escape. In Japan, meanwhile, Professor Kondow has been looking at the microscopic reverse process, the propensity of slow electrons to stick onto closed shell neutral clusters. He has found that the slow electrons are efficiently attached to create a negatively charged clusterion. It is likely that the two groups are carrying out complementary probes of the same essential physics and the goal of the cooperative project is to bring their efforts together to find a unified description of these phenomena.
