Electron Compton scattering on solids- a feasibility experiment on a PEELS system

Abstract

Abstract. 2014 ECOSS (Electron Compton Scattering on Solids) is a powerful method in order to obtain the momentum density distribution of conduction electrons. Apart from the Bragg-Compton channel coupling which produces a strong and often irregular background, the main problem in ECOSS has been the low count rate at scattering angles where the impulse approximation is valid. Simulations showed that the Gatan 666 PEELS should be capable of producing spectra of sufficient accuracy within a dwell time of some 100 s, when dark current and flat field corrections are applied. Prelimi [5][6][7][8]. In the past decade the increasing availability of PEELS systems [9] has offered new possibilities for previously unfeasible energy loss experiments such as ECOSS.As yet, the indirect detection of electrons via a YAG scintillator seems to be the method of choice for PEELS [10,11]. As a detector, linear PDAs [10,11,15] or two-dimensional CCDs [12,13,16] [14]. Eventually, for the resolution given above, (0394E = 5 eV, 039403A9 = 9 x 10-8sr) (2) and a scattering angle of 34 mrad at 300 kV, we calculate a partial cross section in the Compton maximum: Acr = / / ~203C3 ~E03B403A9dE d03A9 = 3 x 10-31 M2 /atom. (1) The overall momentum resolution Aq in an experiment is governed not only by the energy resolution given in equation (2)

Investigation of Electron Momentum Density in Carbon Nanotubes Using Transmission Electron Microscopy

“…In electron microscopy, the electron Compton scattering from a solid (ECOSS) is measured via the electron energy-loss spectrum (EELS) acquired in diffraction mode at large scattering angles, performing an energy scan across the Bethe ridge (Williams & Bourdillon 1982; Williams & Thomas 1983; Williams et al,1984; Schattschneider & Exner, 1995). It has been demonstrated that ECOSS yields a result that is equivalent to photon Compton scattering for the electron momentum distribution of the scatter (Schattschneider et al, 1991; Manninen, 2000). The advantages of the ECOSS technique are a short recording time, a high momentum resolution, a nanoscale spatial resolution, and the additional information available from analytical TEM (Jonas & Schattschneider, 1993).…”

Electron Compton scattering in a symmetric two-beam scattering geometry

“…Recent work has shown the feasibilty of our combined Jeol 200CX-TEM, GATAN 666-PEELSsystem for experimental Compton work [16,8,17]. The effective momentum resolution, depedend on the angle of convergence of the primary electron beam incident on the specimen, spherical and chromatic aberration of the post specimen lenses, the diameter of the spectrometer and finally by the energy resolution, which can be achieved at present with our system is 6p% = 0.135 atomic units 1 [9].…”