Thermal desorption spectra of hydrogenated and water treated diamond powders

The thermal desorption mass spectra of hydrogenated and water treated diamond powders were measured in the range from room temperature to 1250°C. After preliminary outgassing up to 1150°C, samples were either hydrogenated under 1 Pa hydrogen at 500–1000°C or treated in water vapor at room temperature to 800°C. Hydrogenated diamond exhibited two desorption peaks due to H₂ at about 900 and 1050°C, while water treated one desorbed mainly H₂ and CO, and small amounts of H₂O and CO₂. Oxidation after hydrogenation and treatment with a mixture of hydrogen and oxygen showed some correlation between adsorption states of hydrogen and oxygen. The maximum amount of hydrogen desorbed (0.81 × 10¹⁵atom/cm²) was only one-third of the valu estimated as full surface coverage.