This award will support collaborative research in physics between Dr. Gwyn Williams, Brookhaven National Laboratory and Dr. Paul Dumas, Laboratoire de Spectrochimie Infrarouge et Raman, Thais, France. The objective of the project is to study low frequency modes of adsorbates on metal and semiconductor surfaces. Recent developments in infrared synchrotron radiation sources have led to the demonstration of their utility as a probe of low frequency absorbate-substrate vibrational modes. Such low frequency vibrations of adsorbed atoms and molecules contain direct information on the adsorbate-substrate bond, which controls the stability, reactivity and mobility of adsorbates. Few techniques can access these vibrations. Electron Energy Loss spectro-scopy (EELS) has provided the most abundant information due to its particularly good sensitivity. However, its resolution has limited its use for line-shape and isotopic shift studies, as well as for work at higher pressures. In this project, the US and French investigators will use the new infrared synchrotron radiation facility at Brookhaven to perform both and EELS studies on surfaces of transition and noble metals and semiconductors in the low frequency region, combining their expertise EELS (on the French side) and surface reflection-absorption spectroscopy (on the US side). Dr Williams is internationally recognized as a leader in synchrotron radiation spectroscopy and is responsible for the development of the far-infrared beamline at Brookhaven. Dr. Paul Dumas has developed an outstanding surface vibrational laboratory, including research on infrared, electron energy loss, and Raman and laser spe- ctroscopies. Results of this research are expected to contribute to the understanding of the geometry and bonding of adsorbates on surfaces, still one of the most important problems in surface science.
