Latest developments in (e,2e) on solids

Abstract: Recent progress in the application of the (e,2e) technique for elucidating the electronic structure of condensed matter is discussed. Particular emphasis is given to the de-scription of a new third generation electron momentum spectrometer, which operates with an incident beam energy of 20-30 keV, uses asymmetric non-coplanar scattering kinematics with scattered electrons emerging at polar angles 8. = 14", and the ejected electrons emitted at 4e = 76". A range of scattered and ejected electron energies (20eV) and azimuthal angles (-18 " 5 4, 5 18",- 7 O < q5e-.rr 5 7 O) are detected in parallel by means of two-dimensional position sensitive detectors. Software determines the energies and angles of the detected elec-trons, corrects for flight times through the analysers, and determines the separation energy and momentum for each event. With a 5nm amorphous carbon membrane, the true signal rate is 6Hz and the signal to background ratio is 1 with an incident current of 100nA. Without monocroma-tion of the incident beam the energy resolution is l e v and the momentum resolution is 0.15au. The spectral momentum densities obtained for evaporated amorphous carbon are compared with theoretical results.