ELECTRONIC-STRUCTURE OF AL-LI-CU QUASI-CRYSTAL - PHOTOEMISSION AND INVERSE PHOTOEMISSION-STUDIES OF ICOSAHEDRAL AND CRYSTALLINE PHASES

Photoemission and inverse photoemission measurements are reported for icosahedral and crystalline phases of Al-Li-Cu with similar compositions. In the photoemission spectra, Al and Li core states of the icosahedral quasicrystal are shifted to larger binding energies from those of the crystalline phase by 0.4 eV, in contrast to negligible shift of Cu states. A gaplike feature of the density of states is observed in the inverse photoemission spectra of the quasicrystal just above the Fermi level. Comparison between the theoretical calculation and the experimental results of the crystalline phase is discussed.