Electron Compton scattering in a symmetric two-beam scattering geometry

Abstract

Abstract. 2014 The aim of this work is to present an experimental procedure to measure directional Compton profiles by means of electron energy-loss spectroscopy in the transmission electron microscope. In order to obtain unique profiles with a well defined orientation in momentum space a symmetric two-beam scattering geometry taking advantage of crystal symmetry was developped. Measurements on single crystal silicon are discussed in comparison to results of other Compton scattering techniques and theoretical calculations.

Towards Electron Energy Loss Compton Spectra Free From Dynamical Diffraction Artifacts

“…Jonas and Schattschneider observed better agreement between their electron Compton measurements and the same γ-ray result (see Fig. 6a of Jonas & Schattschneider, 1993). The Compton signal in Jonas & Schattschneider (1993) was however acquired at a much higher peak energy of ∼1 keV and therefore higher scattering angle, which may have resulted in a more favorable (i.e.…”

“…The scattering angle for the kinematical and dynamical measurements are similar (49 mrad), and therefore the Compton peak energy should be approximately equal [equation (1b)]. Furthermore, due to the symmetry of the diamond cubic silicon unit cell, the Compton scattering vectors for the 004 and unscattered beams are both crystallographically equivalent (Jonas & Schattschneider, 1993). Therefore, any J ( p z ) anisotropy should also have no effect on the measurement.…”

“…The simulations do not take into account any anisotropy in J ( p z ), although this introduces only a minor error (~1%; Cooper et al, 2004). In principle, the anisotropy can easily be incorporated if J ( p z ) has been parameterized in lattice harmonics (Jonas & Schattschneider, 1993). Compton profiles for each slice along the specimen thickness direction was calculated as described previously and summed to give the final result.…”

“…6a of Jonas & Schattschneider, 1993). The Compton signal in Jonas & Schattschneider (1993) was however acquired at a much higher peak energy of ∼1 keV and therefore higher scattering angle, which may have resulted in a more favorable (i.e. closer to kinematical) specimen diffraction condition.…”

“…A limited number of electron Compton measurements have been performed, such as on carbon-based materials (Williams et al, 1984; Exner et al, 1996; Feng et al, 2013, 2019; Talmantaite et al, 2020) and silicon (Jonas & Schattschneider, 1993; Exner & Schattschneider, 1996). Although the Compton intensity is comparable to phonon scattering in low atomic number solids (Eaglesham & Berger, 1994), its analysis using EELS has not been as widespread as X-ray and γ-ray photon-based methods.…”