Ion-induced M X-ray emission from heavy lanthanides

Abstract Thick targets of several heavy lanthanide (HoLu) compounds were bombarded by protons and 3 He ions of 3 MeV/amu, and M α and M β X-rays were measured with a crystal spectrometer. Ionization probabilities of the N-shell for zero impact parameter were obtained from the X-ray intensity ratio for proton and 3 He ion impacts. A shell dependence of the ionization probability was found in a scaling plot. X-ray spectra of lanthanide compounds were compared and no chemical effect was observed. This result is considered to be due to the fact that the main component of M α and M β lines is for radiative transition after the refilling of the 4f orbit (3d −1 4f n +1 →4f n ) where n denotes the number of 4f electrons of the target atom before ionization.