INNER-SHELL IONIZATION CROSS-SECTIONS AND APERTURE SIZE IN ELECTRON-ENERGY-LOSS SPECTROSCOPY

Electron-energy-loss spectra have been recorded as a function of incid ent beam orientation for K-shell ionization of C in diamond. The resul ts show a strong orientation dependence. We show that a common approxi mation that is often used in calculating the (total) cross section for energy-dispersive x-ray analysis cannot be made for electron-energy-l oss spectroscopy when the acceptance angle of the detector is sufficie ntly small.