Measurement of structure in the energy distribution of slow secondary electrons from aluminum

The number of secondary electrons per unit energy, N (E), and the derivative dN/dE have been measured carefully for clean and contaminated aluminum using a four-grid hemispherical retarding-field energy analyzer. At primary beam energies of 0.5, 1.0, and 1.5 keV, a broadened curve of N (E) vs energy E was obtained for clean aluminum; the more normal narrow curve was obtained when the surface was contaminated with oxygen. This structure is believed due to plasmon decay excitation of electrons in the solid.