Professor Strauss is supported by a grant from the Experimental Physical Chemistry Program to study the structure and dynamics of molecules in condensed phases in the presence of large amplitude motions. The principal experimental techniques employed in this research are high resolution Fourier transform infrared spectroscopy and infrared laser diode spectroscopy. Vibrational spectroscopy, vibrational excitation methods, and theoretical analysis will be used to explore the structure and dynamics of condensed phases. Emphasis will be on chemical systems that illustrate important general methods or elucidate important intermolecular interactions. The effect of very fast reactions on observed vibrational frequencies will be studied with the intention of developing techniques for determining reaction rates directly from spectra. Infrared excitation or "holeburning" in crystals will also be used to provide information on various dynamical processes such as molecular rotation and return to equilibrium by quantum mechanical tunneling. Investigation of holeburning at high resolution will be used to determine homogeneous/inhomogeneous linewidths and the relationship between spectra, structure and strain.