Adsorption of methyl radicals on diamond C(111) surface studied by synchrotron radiation photoemission

The interactions of methyl radicals and azomethane molecules with the diamond C(111) surface have been studied by synchrotron radiation excited photoemission in both valence band and core level spectral regions. It is found that azomethane is adsorbed intact at low temperatures and completely desorbed above 200 K. Characteristic emission bands are identified in the valence band. Adsorbed methyl radicals exhibit a broad feature centered around 10 eV binding energy. The species is detectable as well in the C(1s) region as a shoulder on the higher binding energy side of the diamond peak. The chemical effects on the surface due to alternate sequential exposures of H and CH3 are also investigated and briefly discussed.