Electron momentum spectroscopy of surfaces

Electron momentum spectroscopy [binary (e,2e) spectroscopy] using transmiss ion geometry is a unique experimental tool for imaging the electron momentu m distribution in gas phase samples as well as in thin films. In a solid, t he electron momentum distribution is related to the band structure. Develop ment of the (e,2e) technique using a more versatile reflection geometry is attractive since a much wider range of surfaces could be studied. The desig n of a new reflection (e,2e) spectrometer is presented. It is based on a tw o-step scattering model in which an incident electron successively reflects and ejects a valence electron from the surface. The scattered and ejected electrons are detected in coincidence and their energies and momentum vecto rs are simultaneously determined using a high throughput 90 degrees truncat ed spherical electrostatic analyzer and position-sensitive detectors.