The interaction of oxygen and hydrogen on a diamond C(111) surface: a synchrotron radiation photoemission, LEED and AES study

Abstract

We report an investigation on the adsorption of atomic O and coadsorption with H on a diamond C(111) single crystal surface employing the core and valence level synchrotron radiation photoemission (SRPES) technique, Auger electron spectroscopy (AES), and low-energy electron diffraction (LEED). Additional emission bands in the valence spectrum and a shoulder peak to the higher binding energy of the C 1s core level are found after oxygen exposure in the annealed C(111)-(2 × 1) reconstructed surface, indicating the formation of CO bonds on the surface. The CO reaction, however, does not convert the (2 × 1) reconstructed phase to the bulk-truncated (1 × 1) structure. Even at a saturation coverage of O, the LEED pattern shows the (2 × 1) structure, and the Auger and the photoemission spectra exhibit the characteristics of the reconstructed surface. This suggests a bonding of the O atoms to the (2 × 1) Π-bonded chain. The O-covered surface exposed to H atoms can drive the O from the surface, where it is replaced by H. Only a small amount of O is left on the surface. AES, LEED and SRPES data show the typical features of an H-terminated (1 × 1) state for the H/O/C(111) coadsorbed surface.