Surface state mediated plasmon decay in Al(100)

We present the results of a coincidence experiment aimed at studying the role of plasmons and electronic band structure in the emission of secondary electrons from an Al(100) sample. We measured the spectrum of secondary electrons in coincidence with photoelectrons that have scattered inelastically inside the solid and have excited a bulk plasmon. In this paper we put in evidence that the coincidence energy spectrum of the emitted electron is modulated by the density of occupied states of the sample under investigation. This interpretation is supported by comparing the coincidence energy spectrum with the calculated band structure of the Al(100) surface. The comparison suggests that the coincidence spectrum is dominated by the emission of electrons coming from the Al surface state; it also suggests that, even in the case of bulk plasmon excitation, secondary electron generation is dominated by decay that happens at the immediate surface of the solid.