ar-threshold absolute M-shell x-ray production cross sections of Au and Bi by electron impact

摘要

Absolute M-shell x-ray production cross sections have been measured and calculated for Au and Bi forelectron incident energies from close to the ionization threshold up to 38 keV. The experimental cross sectionswere deduced from Ma x-ray intensities emitted from ultrathin Au and Bi samples deposited on self-supportingC films. The measurements were performed on an electron microprobe using several wavelength-dispersivespectrometers. The x-ray production cross sections were also evaluated theoretically using ionization crosssections calculated from the plane-wave and the distorted-wave Born approximations. Experimental results arecompared with the calculated cross sections and also with the results of two analytical formulas widely used inmany applications. Good agreement is found between the measured cross sections and the predictions from thedistorted-wave Born approximation, which indicates that this approximation is suited for the calculation ofM-shell ionization cross sections of heavy elements.