Experimental determination of cross sections for K-shell ionization by electron impact for C, O, Al, Si, and Ti

Abstract

Cross sections for K-shell ionization by electron impact were determined from films of Al, Si, and Ti and their oxides deposited on carbon substrates, for incident energies between 2.5 and 25 keV. The spectral processing of the x-ray emission spectra took into account corrections due to the presence of a spontaneous oxide layer formed on the monoelemental films and to the supporting material. Carbon K-shell ionization cross sections were determined from the contribution of the substrate to the measured spectra, while for oxygen, data from the three oxide films were taken. The mass thickness of the coatings was characterized by x-ray reflectivity. The results obtained were compared with other experimental data sets, semiempirical approaches, and theoretical models. © 2012 American Physical Society.