Incident-energy dependence of 3p electron energy-loss spectra of nickel

The intensities of two features in the 3p electron energy-loss spectrum of nickel, a dip prior to the threshold and a satellite ～ 12 eV above the threshold, are observed to systematically decrease as the incident electron energy is lowered from 1000 to 150 eV. These intensity changes indicate a dependence of the matrix elements for each excitation on momentum transfer as the incident energy is decreased, in part through changes in the strength of Fano interference near threshold.