Electron energy-loss spectroscopy of the metals Pd, Cu and the ordered Cu75Pd25(1 0 0) alloy

Electron energy-loss spectroscopy has been employed for investigation of the electronic structure of the metals Pd, Cu and the ordered Cu75Pd25(1 0 0) alloy surfaces. Electron energy losses have been collected using primary electron beam energies ranging from 150 to 800 eV. All of the energy losses observed in these samples can be explained in terms of three types of loss mechanisms, namely, electronic transitions involving excited states, excitation of plasma oscillations and ionization of core levels. An essential deviation of the plasmon losses from the theoretical value as calculated on the basis of the free-electron gas model was found for Pd, Cu and the Cu75Pd25(1 0 0) alloy. Using analysis of the intensity of surface and bulk plasmons we can define the interval of primary electron energy E0, where the electron beam scans only the near surface region. Experimental data are compared with optical data obtained by LMTO-ASA calculations