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

Abstract

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