Spatial concentration and temperature distribution of CH radicals formed in a diamond thin-film hot-filament reactor

Spatial concentration and temperature profiles of the CH radical in a hot-filament chemical vapor deposition reactor are measured by cavity ring-down spectroscopy. The CH concentration is found to be on the order of 1011 molecules/cm3. The spatial distribution indicates that CH formation primarily occurs at or very near the filament. At a distance of 2 mm from the filament the [H]/[H2] ratio is determined to be 0.011±0.003.