Transmission (e,2e) coincidence measurements of thin evaporated carbon, graphite, and aluminum–aluminum oxide foils

Symmetric transmission (e,2e) coincidence data are presented from the valence region of evaporated amorphous carbon, graphite, and aluminum–aluminum oxide thin (between 100 and 200 Å) foils. The count rate of this technique, within the plane-wave-impulse approximation, is directly proportional to the spectral momentum density. The data were accumulated at a probe energy of 7.5 keV with typical energy and momentum resolutions of 4.5 eV and 0.9 Å ${}_{}{}^{\mathrm{-}1}{}_{}{}^{}$ full width at half maximum (FWHM), respectively. The aluminum oxide foil was investigated close to 0 Å ${}_{}{}^{\mathrm{-}1}{}_{}{}^{}$ binding momentum with an improved energy resolution of 1.5 eV FWHM. The resolved electron states are related to the S and P nature of the valence electrons in these materials with a small atomic number. The similarity between amorphous carbon and graphite suggests that the amorphous sample was largely graphitically bonded. The results are discussed with special attention paid to the short, electron mean free paths within the solid samples.