Scanning Electron Diffraction Attachment with Electron Energy Filtering

Abstract

A scanning electron diffraction attachment providing for energy analysis of the scattered electrons has been constructed for use in conjunction with a J.E.M. 6AS electron microscope. This attachment permits the direct recording of diffracted electron intensities as a function of angle with an accuracy of ±0.1%. The attachment can be operated to exclude all but the elastically diffracted electrons, or, alternatively, to detect electrons with a measurable amount of energy loss. The electrostatic energy analyzer has an energy cutoff of better than 1.1 eV out of 100 keV. The angular resolution of the instrument is presently 2.2×10−4 rad, with minimum detectable electron intensity of 10−14 A. The instrument performance is demonstrated by studying the effect of inelastic scattering in the diffraction pattern of aluminum, and by recording the plasma loss spectrum of aluminum. The filtered profiles have narrower peaks than the unfiltered ones and better peak resolution, and the contrast between peaks and background is enhanced. At low values of the scattering vector where the inelastic background is very intense, its removal reveals diffraction effects which otherwise would have been invisible. The attachment does not interfere with the conventional plate microscopy and diffraction, and provides, thereby, a method of energy analyzing the direct microscope image as well.

On the Investigation of the Structure of Amorphous Substances by Means of Electron Diffraction

“…By placing the scanning coil directly beneath the specimen it could be reached that the maximum angle under which the electron beam passes the filter amounts to 0.81°, which means a deviation of 4 mm directly above the detector. If one assumes a quadratic dependence from the angle [6], this corresponds to 0.4 eV. This is a value which cannot be reached by ring electrodes with simple (circular) profiles.…”

“…The filter is connected in parallel to the electron source. So both parts follow eventual drifts in the same manner and therefore these have no influence on the energyresolution [6]. The main feature of the present electrostatic filter is the exact cut-off beneath a defined energy and at the same time a good trans- via free access parency for all energies lying above.…”

“…The line width of the energy distribution of the primary electrons amounts 4 to 5 eV. The maxima in the spectra of Germanium and of Mn73Si27 at about -7 eV are ascribed to inelastic scattering connected with plasmon excitations [6,10]. Thus we recognize that the plasmon scattering can be separated from the elastic part of the spectrum.…”

“…By forming the first derivative of these curves one obtains energy spectra as given in Figure 3 [6].…”

Structure of metallic glasses

“…Even this average is not accurate, as the analysis of diffraction patterns from a multicomponent glass involves the use of approximations that are not always justifiable. However, recent advances in experimental techniques [33][34][35][36][37] have made it possible to obtain more accurate diffraction data from glasses. The advances in theory [38][39][40] have made a more precise analysis of diffraction data from binary glasses possible.…”