VIBRATIONAL-SPECTRA OF HYDROGEN ON DIAMOND C(111)-(1X1)

Infrared-visible sum-frequency generation was used to obtain vibrational spectra of hydrogen on C(111). From a fully relaxed (1 x 1) surface, a single sharp peak at approximately 2830 cm-1 was observed, which can be identified as the CH stretch mode from H on top sites. With the surface freshly transformed from (2 x 1) to (1 x 1), however, another peak at a higher frequency was detected. This is attributed to H adsorbed on a metastable (1 x 1) structure.