Abstract
Recent studies on high-Tc oxide superconductors by using various electron spectroscopies have been reviewed. Main novel results obtained for the past half a year can be summarized as follows; (1) Unoccupied O 2p holes above the Fermi level have been observed with YBa2Cu3O7-x. (2) A photon-energy-dependent emission from the states near the Fermi level was observed with a single crystal of YBa2Cu3O7-x (001). The emission was apparently of angular dispersion and of photon-energy dependence. (3) Combined XPS and TD studies suggest that the appearance of the superconductivity strongly related to the Cu-O bonds along a one-dimensional chain.
