ELECTRONIC-STRUCTURE OF THE ORGANIC SUPERCONDUCTOR K-(BEDT-TTF)2CU(NCS)2 STUDIED BY ANGLE-RESOLVED PHOTOEMISSION SPECTROSCOPY

In the photoemission spectra of the kappa-(BEDT-TTF)2Cu(NCS)2 surface, two characteristic structures were observed at the binding energies of approximately -7.5 eV and approximately -11.5 eV, which were attributed to the pi- and sigma-bonding states, respectively, in comparison with the results of the molecular orbital (MO) calculations. Polarization dependence appearing in the spectra was comprehensively interpreted by the electronic structures calculated for those states, which is in good agreement with the results previously obtained using a scanning tunneling microscope.