Vibrational spectra of hydrogen on diamond C(111)-(1×1)

Infrared-visible sum-frequency generation was used to obtain vibrational spectra of hydrogen on C(111). From a fully relaxed (1×{}1) surface, a single sharp peak at {~}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×{}1) to (1×{}1), however, another peak at a higher frequency was detected. This is attributed to H adsorbed on a metastable (1×{}1) structure.