Surface gap and surface electronic states in CuGeO3 Single Crystal

The surface and bulk electronic excitations of CuGeO3 are investigated by means of electron energy loss and polarized X-ray absorption spectroscopy. CuGeO3 shows a surface charge transfer gap of about 3.0±0.3 eV. The unoccupied oxygen derived density of states, as probed by X-ray absorption at the O 1s edge, is in good agreement with recent many-body calculations