VALENCE-BAND PHOTOEMISSION-STUDIES OF LIGA ZINTL INTERMETALLIC COMPOUND

The valence band photoemission spectra of LiGa Zintl intermetallic com pound were measured at various photon energies by using a synchrotron radiation source, and were compard with the existing RAPW band structu re calculations. The very low intensity of photoemission from the top of the valence band indicates that the s-to-p charge promotion believe d to explain the bonding in this Zintl compound is less significant th an that predicted by theory. The measured binding energy of 18.8 eV of the Ga-3d doublet states places these states about 7.7 eV below the b ottom of the valence band, in contrast with the calculated value of 4. 5 eV. A clear structure observed at 13 eV binding energy has no counte rpart in the theoretical DOS distribution. Its ambiguous origin is dis cussed in relation to possible interband excitations, or its incorpora tion into a wider valence band than that resulting from the RAPW theor y.