Electron-momentum spectroscopy of crystal silicon

Electron-momentum spectroscopy based on the (Formula presented) reaction has been used to observe the energy-momentum density of valence electrons in the [110] direction for an ultrathin, free-standing film of crystalline silicon. An asymmetric scattering geometry is used in which the incident, scattered and ejected electron energies are 20.8, 19.6, and 1.2 keV, respectively. The measurement is complicated by the possibility of diffraction of the free electrons. The theory of the reaction including diffraction is summarized and applied to experiments with different target orientations. The orientation is determined from an independent electron diffraction experiment. Very good agreement between theory and experiment is observed.