Experimental determination of L -subshell x-ray production cross sections for La, Ce, Pr, and Nd by electron impact

Abstract

L-subshell x-ray production cross sections induced by electron impact were determined for La, Ce, Pr, and Nd in the incidence energy range of 5.7-25 keV. The experiments were carried out by irradiating thick samples in a field-emission scanning electron microscope equipped with an energy-dispersive spectrometer. The x-ray spectra were then analyzed using a previously developed optimization software, which accounts for bulk effects through a model for the ionization depth distribution function. The x-ray production cross sections obtained were compared with theoretical predictions, using different relaxation data reported in the literature. A good agreement is obtained for the L2 and L3 subshells when the DWBA model is used along with the relaxation parameters reported by Perkins et al. However, for the L1 subshell, the theoretical curves systematically underestimate the measurements in the high energy region, evincing the need for further determinations of the fluorescence yield coefficient for this subshell.