Inverse photoemission and soft X-ray emission spectra of AlNiCo decagonal single quasicyrstal

Inverse photoemission spectra (IPES) of a decagonal single quasicyrstal Al72Ni12Co16 have been measured for various incident electron energiesE i together with its AlL 2,3 soft X-ray emission spectra (SXES). Both IPES and SXES show low intensity near the photon energy corresponding to the Fermi level, which is consistent with an opening of a pseudo-gap across the Fermi level. The IPES shows no strong resonance enhancement, suggesting apparently small density of the transition metald states above the Fermi level. However, constant final state spectra of the inverse photoemission reveal faint humps aroundE i = 62 and 76 eV, which might indicate resonances due to the Co and Ni3d-derived states, respectively. A shoulder structure at the low photon energy side of the main band in the AlL 2,3 SXES becomes prominant for the lower incident electron energy and is tentatively ascribed to the Ni3p emission band.