L-subshell ionization cross sections for Hf, Ta, and W byH+andHe+bombardment

Abstract

X rays resulting from L-subshell vacancies in Hf, Ta, and W produced by bombarding thin targets with H/sup +/ (0.6--2.5 MeV) and He/sup +/ (1.2-- 4.2 MeV) were detected by Si(Li) spectrometry. Ionization cross sections were obtained by using the above measurements, branching ratios from theoretical calculations, and values of the fluorescence yields and Coster-Kronig factors by interpolating from experimental data. The observed projectile-energy dependence of the L/sub II/-subshell ionization cross section is reproduced reasonably well by the plane-wave Born approximation (PWBA), but the introduction of relativistic, trajectory, and binding corrections (PWBA-BTR) are essential for the description of the L/sub I/ and L/sub III/ data. Scaling of the H/sup +/ and He/sup +/ data shows that one agrees well with the other. The behavior of the ionization cross section versus bombarding energy is correlated with some special features of the electronic bound-state wave functions.