This program is dedicated to the study of dynamic, electronic, and optical properties of simple systems at extreme pressures and low temperatures. The techniques used in the experiments are principally inelastic scattering of light. In the recent past, most of the light scattering has been spontaneous Raman scattering. More recently the laboratory added facilities to do coherent anti-Stokes Raman Scattering (CARS) and other four wave mixing experiments. Among these, two-photon resonances are being exploited to probe electronic structure of samples within anvil cells. A particular advantage of the multiphoton technique is the ability to examine electronic states having energies higher than the maximum photon energy at which high pressure windows, e.g. diamond, are transparent. They propose to exploit this advantage in a program of study of electronic excited states in hydrogen and deuterium and in exygen, nitrogen, and benzene at extreme pressures.