The Experimental Physical Chemistry Program support Martin F. Jarrold in his continuing studies to determine the structure of medium-sized clusters using gas phase ion mobility measurements. The speed with which a gas phase ion moves through a buffer gas under the influence of a weak electric field depends on its geometry. Although some information about the geometries can be deduced from the mobilities, more than one geometry can have the same mobility. Thus, Jarrold proposes to couple a recently-constructed high resolution apparatus with a magnetic-bottle anion photoelectron spectrometer. Using this approach, photoelectron spectra will be measured as a function of geometry and cluster size for carbon, silicon, and germanium clusters of up to hundreds of atoms. Atomic clusters are small pieces of material containing from a few to several thousand atoms. For a variety of reasons, the physical and chemical properties of these species are different than those of the bulk material. Examining the properties and determining how they change as a function of cluster size has been the object of a major research effort for the last ten years. Structure generally controls the physical and chemical properties of any material. Thus information about the geometric structure of atomic clusters is critical for understanding their size-dependent properties. These studies will substantially increase our understanding of the structure and bonding in clusters of the Group 4 (carbon, silicon and germanium) elements.
