In this project in the Experimental Physical Chemistry Program Dr. Kenneth R. Leopold will use tunable, high-resolution tunable far infrared spectroscopy to study 1) potential energy surfaces and internal dynamics of weakly-bound complexes and 2) the dynamics of intramolecular proton transfer reactions. Work in the first area will focus on systems with multiple secondary potential minima and large amplitude vibrations. These are important as models for more general chemical complexes which exhibit competitive binding sites. In the second area intramolecular proton transfer dynamics will be investigated for the internally hydrogen bonded molecule molecule malonaldehyde. In particular, the tunneling splittings produced by the proton motion will be examined in the presence of a quantum of vibrational excitation in several of the skeletal vibrational modes of the molecule. %%% Hydrogen bonding and other weak intermolecular interactions are important because they can steer the course of many chemical reactions of vital technological and biological importance. It is therefore important to understand these interactions at a fundamental level. Dr. Leopold will add to this understanding by probing the strength and nature of intermoecular interactions using a special, high resolution infrared spectrometer constructed in his laboratory.