A surface reaction with atoms: Hydrogenation of sp- and sp2-hybridized carbon by thermal H(D) atoms

Abstract

Hydrogen containing carbon (C:H) films have been prepared by ion beam deposition of 160 eV ethane ions on a carrier consisting of a Pt(111) single crystalsurface covered with a monolayer of graphite. Several monolayers thick filmsdeposited at 350 K contain hydrogen bound to sp, sp 2, and sp 3 hybridized carbon.Vibrational spectroscopy reveals that thermal D(H) atoms directed to the C:H filmsurface hydrogenate unsaturated CH groups at the surface and transform sp and sp 2 hybridized carbon to sp 3. The observed reaction mechanism explains the microscopic processes in chemical erosion of graphite by hydrogen atoms which is a crucial reaction step in the low pressure synthesis of diamondlike carbon.