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 description 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 φ_s, and the ejected electrons emitted at Φ_e = 76°. A range of scattered and ejected electron energies (20eV) and azimuthal angles ([MATH]) are detected in parallel by means of two-dimensional position sensitive detectors. Software determines the energies and angles of the detected electrons, 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 monocromation of the incident beam the energy resolution is 1eV and the momentum resolution is 0.15au. The spectral momentum densities obtained for evaporated amorphous carbon are compared with theoretical results.