Dr. Kenneth Leopold is supported by a grant from The Experimental Physical Chemistry Program to perform studies on the structures and large amplitude motions of weakly bound van der Waals complexes and metal clusters. Dr. Leopold will use a new state-of-the-art far infrared technology to study the vibrational properties of these clusters. This very high resolution spectroscopic information is not available through any other experimental approach. State-of-the-art far infrared technology featuring high sensitivity, high resolution, and complete coverage throughout the far infrared region will be combined with established methods of supersonic jet expansions to study the low frequency vibrational spectra of a wide variety of van der Waals species. This work is distinct from the majority of other studies on van der Waals complexes in that it involves direct excitation of the soft intermolecular vibrations, and is made possible by a new technique in which tunable far infrared radiation is generated from the difference frequency between two carbon dioxide lasers. The results will be crucial to the testing and development of new theoretical methods for computing intermolecular potential surfaces and for treating the problem of large amplitude motion in molecules. In addition, the examination of rotationally resolved vibrational spectra of metal trimers will provide high quality information regarding the structure, vibrational frequencies, and barrier heights to pseudorotation in these species.
