Secondary electron and backscattering measurements for polycrystalline copper with a spherical retarding-field analyser

A full spherical retarding-field energy analyser with three grids was made to measure the total secondary electron yield σ, the backscattering coefficient η, and the secondary electron spectrum N(E) as a function of angle of incidence and primary energy in UHV. The instrumental effects of the grid meshes in the measurement of N(E) were minimized by using the sample-bias-modulation technique. The values of σ and η for polycrystalline copper were found to be rather higher than previously published values. The N(E) curves are almost independent of the angle of incidence (θ) between θ=0° and 40°. The halfwidth of N(E) increases as the primary energy is reduced. These suggest that in metals the electron-electron interaction is dominant. Also, the dependence of N(E) on primary energy is believed to be caused by variations in both the excitation depth and the initial energy distribution of internal secondaries.