THE CHEMISORPTION OF HYDROGEN ON DIAMOND SURFACES STUDIED BY HIGH-RESOLUTION ELECTRON-ENERGY-LOSS SPECTROSCOPY

Species chemisorbed on diamond (111) and (100) surfaces, which had been grown by the microwave-plasma-assisted chemical vapour deposition (CVD) method, were investigated by low energy electron diffraction and high resolution electron energy-loss spectroscopy (HREELS). Boron-doped semiconducting diamond surfaces grown homoepitaxially on natural diamond were used as substrates in order to avoid charging up by the electron beam. C-H stretching vibrations and C-H bending vibrations were observed on both the diamond (111) and (100) surfaces. In the off-specular EELS spectra, two C-H stretching vibration modes (at 2840 and 2912 cm-1) were resolved on the (111) 1 x 1 surface. The two modes observed on the (111) surface are assigned to symmetric and asymmetric stretching vibrations of CH3 species respectively. Only one C-H stretching vibration mode was observed at 2930 cm-1 on the (100) 2 x 1 surface.