Methyl-radical and atomic hydrogen adsorption on C(111) have been studied by infrared-visible sum-frequency vibrational spectroscopy. Methyl iodide, di-tert-butyl-peroxide, and methane passing through a hot filament are used to produce methyl radicals ((Formula presented)). Low-energy (Formula presented) from pyrolytic dissociation at ∼800 °C adsorb intact on the surface, but with surface annealing above 350 °C, convert to tetrahedrally bonded CH. High-energy (Formula presented) produced at ∼1800 °C convert readily to CH upon adsorption. Co-dosing a high-temperature (∼800 °C) C(111) substrate with hydrogen and methane via a hot filament at ∼1800 °C yields only the stable tetrahedrally-bonded CH-species on the surface. They appear to stabilize the diamond surface structure. The coverage is not full, leaving sites open for (Formula presented) to adsorb and convert to CH as is necessary for chemical vapor deposition diamond growth.
|Number of pages||9|
|Journal||Physical Review B - Condensed Matter and Materials Physics|
|State||Published - 1 Jan 1996|