The reaction of atomic hydrogen with a-C-H and diamond films.

The surface reaction of thermal atomic hydrogen with polycrystalline diamond films, prepared by hot-filament assisted chemical vapour deposition has been investigated. Atomic beam techniques in combination with mass spectroscopic detection of the formed product molecules, have been used to study hydrogen-induced erosion. When compared with a-C:H films, the reaction of H high 0 with diamond films is negligible. The yield is orders of magnitude smaller and reaches maximum values below 10 high -4 around 500 K. After starting the atomic hydrogen exposure, a transient behaviour is observed with 10 times higher yield, probably due to a reaction with remaining amorphous carbon.