PLURAL-SCATTERING DECONVOLUTION OF ELECTRON ENERGY-LOSS SPECTRA RECORDED WITH AN ANGLE-LIMITING APERTURE

We examine the validity of Fourier-logarithmic deconvolution for removing plural-scattering peaks from a transmission-electron energy-loss spectrum, in the case where the spectrum has been recorded in the presence of an angle-limiting collection aperture. Experimental results indicate that the procedure is accurate to better than 3% within the plasmon-loss region, for apertures commonly used in a transmission electron microscope. This degree of accuracy implies that the fraction Fn of electrons which pass through the aperture (after inelastic scattering of order n) obeys the relation Fn≈(F1)n. Computer calculations of the angular distributions of double and triple scattering support this relationship, taking the single-scattering distribution to be Lorentzian and the collection semi-angle to be large compared to the characteristic angle θE. Extending our analysis to the deconvolution of inner-shell ionization edges, the error in the subtraction of double (plasmon+inner-shell) scattering is predicted to be less than 10% for edge energies below 5 keV, assuming 10 mrad collection semi-angle and 100 keV incident electrons. © 1990.