DIFFRACTION AND ABSORPTION OF INELASTICALLY SCATTERED ELECTRONS FOR K-SHELL IONIZATION

An expression for the nonlocal inelastic-scattering cross section for fast electrons in a crystalline environment, which explicitly includes diffraction as well as absorption for the inelastically scattered ele ctrons, is used to carry out realistic calculations of K-shell electro n-energy-loss spectroscopy (EELS) and energy dispersive x-ray (EDX) an alysis cross sections. Our calculations demonstrate quantitatively why , in EDX spectroscopy integration over the dynamical states of the ine lastically scattered electron averages in such a way that an effective plane wave representation of the scattered electrons is a good approx imation. This is only the case for large enough acceptance angles of t he detector in an EELS experiment. For EELS with smaller defector aper tures, explicit integration over the dynamical final states is necessa ry and inclusion of absorption for the scattered electrons is importan t (particularly for thicker crystals).