Felker is supported by the Experimental Physical Chemistry Program to continue his ground-state spectroscopic studies of isolated, neutral molecular clusters, using the technique of mass-selective, ionization-detected stimulated Raman spectroscopy (IDSRS) developed in his laboratory. These studies focus on characterizing the intermolecular vibrational level structures of neutral clusters, with primary goals of obtaining information pertaining to intermolecular potential energy surfaces and collective vibrational modes. Systems for study include (1) hydrogen-bonded dimers, including aromatics with water or ammonia, and water dimers, (2) larger hydrogen-bonded and homogeneous aromatic clusters, and (3) free radicals and their complexes with rare gas atoms and small molecules. The project also includes a computational effort to simulate intermolecular Raman spectra to facilitate assignment of observed bands and the extraction of intermolecular potential parameters from experimental results. The overall goal of this research program is to advance the state of knowledge pertaining to how collections of molecules interact with one another. Outcomes from these studies are expected to impact the development of force fields that are used in computer modeling of condensed phase systems, including biologically important molecules, molecules adsorbed onto surfaces and new materials for technological applications. Discovering detailed properties of water-based clusters, in particular, could have important ramifications for improved understanding of environmental and biochemical systems.
