X-ray absorption spectroscopy study of different solid carbon modifications

Thin chemical vapor deposition (CVD) films of textured diamond (100) and (110) were compared with natural diamond, tetrahedral amorphous carbon, and highly oriented pyrolytic graphite using x-ray absorption spectroscopy at the C 1s absorption edge. Analysis of the intensity ratios of the C 1s --> pi* and the C 1s --> sigma* transitions gives a sp(2)/sp(3) ratio of nearly 15% and 40% in the pretempered CVD C(100) and CVD C(110) samples, respectively. The textured samples were exposed to different hydrogen-hot filament treatments for in situ cleaning and for preparing hydrogen-saturated surfaces. After a severe H-2 hot filament treatment of the CVD C(110) surface a new peak appears at 286.0 eV, 0.6 eV above the graphite C 1s --> pi* transition indicating a new hydrocarbon surface compound. (C) 1997 American Vacuum Society.