Energy Distribution of Secondary Electrons from MgO Single Crystals

The secondary-electron energy distribution from single crystals of MgO has been measured. A dependence of energy distribution on primary electron energy is established. The dependence is consistent with a qualitative interpretation based on the path length of the secondaries inside the crystal. The single-pulse measurements method has been modified to permit greater sensitivity, so that ${10}^4$ electrons per pulse are sufficient for a 30:1 signal-to-noise ratio. Two procedures for establishing the surface potential are compared. Vacua of the order of ${10}^{-10\mathrm{}}$ mm are employed.