This Research Planning Grant will enable Dr. Helen Leung to initiate a research program using fourier transform microwave spectroscopy to investigate weakly bound complexes of unsaturated molecules. In the early phase of the work a a pulsed molecular beam fourier transform microwave spectrometer will be constructed. The average and equilibrium structures of complexes formed from two unsaturated subunits will be determined for the ground vibrational states. Subsequent work will investigate the molecular dynamics of these systems and and the nature of van der Waals forces. This will be done by sampling the potential energy surfaces. It is intended that the work will shed light on the raction dynamics of pericyclic cycloaddition reactions between the subunits. %%% Research Planning Grants are awarded to women who have not yet received federal funding for their research. Dr. Leung will be constructing the equipment necessary to study the weak interactions among certain kinds of molecules. These interactions are very important in biological systems and, in general, in a detailed understanding of how chemical reactions proceed.