HREELS AND LEED OF H/C(100) - THE 2X1 MONOHYDRIDE DIMER ROW RECONSTRUCTION

High resolution electron energy loss spectroscopy (HREELS) and low energy electron diffraction (LEED) have been used to investigate the hydrogen (deuterium) atom exposed diamond (100) surface. HREEL spectra indicate only monohydride species after ex situ exposure of the surface at 800 degrees C to a hydrogen plasma. Likewise, no dihydride is observed after in situ exposure of the surface to hydrogen atoms produced by a hot tungsten filament. In addition, a sharp two-domain 2 X 1 reconstruction is observed by LEED for the hydrogen (deuterium) saturated surface. These data indicate that hydrogenated C(100) assumes the monohydride dimer row reconstruction. A two-domain 2 X 1 LEED pattern is also observed from C(100) following heating to approximately 1050 degrees C and HREEL spectra show no features due to adsorbed hydrogen (deuterium). These data are consistent with the pi-bonded dimer row reconstruction for bare C(100). HREEL spectra of the bare surface show peaks at 710, 1060, and 1280 cm(-1).