Roger E. Miller of the University of North Carolina at Chapel Hill is supported by the Experimental Physical Chemistry Program and the Office of Multidisciplinary Activities to continue his high resolution infrared studies on the state-to-state dynamics of weakly bound complexes. He will focus on the water dimer, which is of particular interest to the theoretical chemistry community, and measure the rotational and vibrational photofragment distributions, scalar and vector correlations, and dissociation energies. In a newer effort, Miller will investigate the intermolecular forces and vibrational energy transfer associated with the scattering of vibrationally excited species from single crystal surfaces. Emphasis here will be on improvements in experimental methods and the investigation of more complex, polyatomic molecules. Molecular clusters of two to tens of molecules loosely bound together can be viewed as the intermediary stage between `isolated` single gas molecules and the extended arrays of molecules that make up the solid. Understanding the behavior of such clusters helps us to better understand the nature of the transition from gas to solid. As it is, clusters are fairly ubiquitous and play important roles in atmospheric chemistry, thus we need to understand the dynamics of their formation and fragmentation, the nature of the forces between the molecules that make up the cluster. The newer effort on the study of the forces that influence how a single gas molecule interacts with a `supercluster` or surface can be viewed as a simple extension of the earlier work by Miller.
