A VIBRATIONAL STUDY OF THE ADSORPTION AND DESORPTION OF HYDROGEN ON POLYCRYSTALLINE DIAMOND

The adsorption and desorption of hydrogen from diamond films were studied in ultrahigh vacuum using high resolution electron energy loss spectroscopy as a probe of surface vibrations. Auger electron and energy loss spectroscopies were also used to characterize the diamond surface. The samples studied were: boron-doped polycrystalline diamond films with chiefly (111) oriented facets. We attribute the observed spectral features to a monohydride species and local sp(3) bonding on the diamond surface exposed to atomic hydrogen. A significant fraction of the hydrogen desorbs from the surface between 950 and 1000 degrees C, although some hydrogen persists even after heating to 1050 degrees C.