We describe an instrument designed for studying the electronic structure of bulk, surface, and deep solid–solid interface. The analysis is made by soft-x-ray emission spectroscopy induced by electron bombardment. The target is placed under ultrahigh vacuum and can be prepared and treated in situ. High resolution is achieved both as concerns the photon energy and the electron-beam energy. Tests have been made in the dispersive mode and in the characteristic isochromat mode. In both cases experimental resolution is in good agreement with the expected one.

AhsbacL The p d a l A I and 0 valence spectral densities of a-and y-alumina in bulk and in the superficial zone of the samples are investigated using x-ray emission spectroscopy induced by electrons. These valence states are mixed over the whole width of the band. We show that changes in the atomic environment affect the hybndizalion of states io a narrow energy range. For the y-phase and superficial zones of the two phases. increased hybridization is'abserved. This is correhted with an increase in the covalent character of A I 4 bonds at the surface and the y-phase. Defect states are observed both in the gap between 0 2s and 0 2p stat= and in the optical gap; for the a-phase, a structure is seen at about 1 eV above fhe top of the valence band which we interpret as due to an oxygen-vacancy state.

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Teachers are gifted with the responsibility of helping their students, their colleagues, and themselves find meaning in their lives. Robert Nash offers his gift of reflection on how best to accomplish this most important work.