Secondary Electron Emission from Simple Metals: Comparative Studies for Al, Mg, and Be

In the secondary electron emission (SEE) from solids, the role of different excitation processes is now as ever of special interest from both the theoretical and the experimental points of view. Depending on the primary energy, the relative importance of different excitation mechanisms related to conduction as well as core electrons will be discussed for different simple metals. So far, first principles results are available only for Al for primary energies up to 10 keV. Starting from a microscopic description of the SEE based on the transport equation formalism, calculations were performed for other nearly-free-electron metals (Mg, Be) up to primary energies used in scanning electron microscopy. In this way, it is possible to obtain more general statements about the role of different excitation processes responsible for SEE. Special attention is devoted to the contribution of emitted electrons stemming from the excitation of conduction electrons by decay of bulk plasmons generated by the primary electron. The different strength of this excitation mechanism in Al, Mg, and Be is related to the different magnitude of the plasmon damping in these metals