Characteristic Energy-Loss Spectra of Titanium, Vanadium, and Chromium

Publisher Website
Google Scholar
Abstract
Electron energy losses in titanium, vanadium, and chromium have been measured on evaporated-film specimens in ultrahigh vacuum. Measurements were made with a retarding-field analyzer, and the surface purity was monitored by Auger spectroscopy. The energy-loss spectra for clean surfaces of these metals showed similarities in line shape and in their behavior toward oxygen adsorption. In the energy range 0–30 eV, the loss spectra were composed of four peaks which we have interpreted as due to a surface-plasma loss, bulk-plasma loss, combination surface-bulk loss, and a second harmonic volume loss. The energy values (in eV) for these four peaks, in the order listed above, were measured as follows: Ti(5.0, 11.5, 17.0, 24.6), V(5.1, 10.5, 16.5, 24.0), and Cr(5.0, 9.5, 15.5, 23.5). Changes in the surface-loss intensity were observed for oxygen coverages on the order of 0.04 monolayer. The measured energies for the bulk-plasma excitation were found not to be in agreement with calculated values according to the classical theory for collective oscillations in solids. The present results are compared with characteristic energy-loss data reported in the literature.