Surface vibrations of diamond C(001)(2x1)

Abstract

Surface vibrations of diamond C(001)(2 X 1) have been studied by means of electron energy loss spectroscopy as well as first-principles theoretical calculations. Several vibrational modes are newly resolved. Outside the bulk phonon band, we observe a surface-derived mode at 172 meV, which is assigned as the dimer stretching mode as predicted by theoretical results. The other losses are in resonance with the bulk phonon band, and thus, they cannot be assigned as pure surface or bulk modes. The dispersions of the loss peaks are measured along the high-symmetry directions of the surface Brillouin zone, where we find nearly localized character of the vibrations along the surface.