This US-Czechoslovak research project between Dr. M. A. Van Hove of Lawrence Berkeley Laboratory and Dr. I. Bartos of the Institute of Physics of the Czechoslovakian Academy of Sciences will study diffraction of excited electron states and of dynamic processes on crystal surfaces. The researchers will explore the dynamic electron processes at metal surfaces, which are relevant for understanding many- body effects that will clarify the behavior of electrons in lower-dimensional systems. Such inelastic effects will be studied in the diffraction of low-energy electrons, by fitting model optical potentials to experimental data. Results may shed light on the electronic structure of unoccupied states above the vacuum level, such as the usual inelastic mean free path in transition metals at energies close to the vacuum level. The work also should benefit the understanding of lifetimes in photochemistry cynamics at surfaces with adsorbates. A further benefit would be better access to very light elements, principally hydrogen, which can induce surface reconstruction. These results would be important in understanding catalysis, crystal growth and properties of nanostructures. This research project in materials science fulfills the program objective of advancing scientific knowledge by enabling leading experts in the United States and Eastern Europe to combine complementary talents and pool resources in areas of strong mutual interest and competence.