THERMAL HYDROGENATION OF DIAMOND SURFACES STUDIED BY DIFFUSE REFLECTANCE FOURIER-TRANSFORM INFRARED, TEMPERATURE-PROGRAMMED DESORPTION AND LASER RAMAN-SPECTROSCOPY

The chemisorbed species on diamond surfaces have been studied by Fourier-transform infrared (FTIR), temperature-programmed desorption (TPD) and laser Raman spectroscopy. Oxidized diamond powders were treated thermally in an H-2 environment. IR spectral changes were followed during the hydrogenation of oxidized diamond powders. We observed CH bonding on diamond surfaces. The amount of CH bonding increased with the temperature of treatment below 900-degrees-C. Above 900-degrees-C, the amount of the CH bonding decreased. Thermally desorbed species were analysed by mass spectrometry. H-2 was desorbed from hydrogenated diamond powders above ca. 800-degrees-C. Close agreement between FTIR and TPD results was obtained. Raman spectra indicated that the disordered graphitic carbon phase was formed above 900-degrees-C.