STRONG EVOLUTION OF THE P-PROJECTED EMPTY DENSITY OF STATES IN PD-AL ALLOYS - AN M4,5 X-RAY-ABSORPTION-SPECTROSCOPY INVESTIGATION

We present a near-edge x-ray-absorption investigation on the Pd M4,5 edge of Pd, Pd0.85Al0.15, PdAl, and PdAl3, and on the Ag M4,5 edge of Ag. A comparison with theoretical results for the pure elements Pd and Ag indicates this kind of spectroscopy to be related to the p-projected density of states above the Fermi level via a --> 3d --> 5p dipole allowed excitation. A direct estimation of the Ag M4,5 core-hole life-time width value (0.4 +/- 0.05 eV) is furthermore accomplished. The dramatic changes of the investigated line shapes on going from pure Pd to an increasing dilution of Pd atoms into an AI matrix host suggest a strong participation of the p states to the formation of the chemical bonding which has been undervalued up to now.