Angular dependence of Ag L-X-rays emission induced by 20–40 keV electron-impact

Abstract

In element analysis of materials, whether the X-ray emission is isotropic plays an import role in the technique of Particle Induced X-ray Emission (PIXE). Thus, it is meaningful to investigate the alignment of vacancy states produced by impact ionization. In this work, the emission of L X-rays for Ag has been measured by electrons at 20–40 keV. In order to study the angular distribution, the characteristic spectra are detected at different emission angles (from 5° to 25° with intervals of 5°). It is found that the emission of Lβ1(L2M4) and Lγ1(L2N4) X-rays exhibits isotropic distribution, while the emission of Lα(L3M4,5) and Lβ2(L3N5) X-rays is anisotropic. With the increase of impact energy, the intensity ratios of Lα/Lβ1 and Lβ2/Lβ1 increase significantly. While the slopes of intensity ratios for Lα/Lβ1 and Lβ2/Lβ1 on emission angle do not change significantly at different impact energy. It indicates that the alignment degree A20 is independent on incident energy from 20 to 40 keV. Consequently, the alignment degree A20 for L3 subshell is deduced to be 0.63 ± 0.10 experimentally.