Measurement and models of electron-energy-loss spectroscopy core-level shifts in nickel aluminum intermetallics

Absolute measurements of the L-edge core-level binding energies are made for nickel-aluminum compounds using electron-energy-loss spectroscopy (EELS). The core-level shifts are found to compare favorably with ab initio calculations of the valence band shifts. The measured EELS oscillator strengths and core-level shifts are used to test the local charge neutrality (LCN) approximation to self-consistency in extended Hückel tight-binding calculations. Within the LCN approximation, the tight-binding calculations can provide estimates of both the core-level shifts and, with the use of the force theorem, the alloy heats of formation for the Ni-Al intermetallics.