L-shell ionization studies of Pb and Bi with α particles

Ionization cross sections for the L subshells of Pb and Bi by α-particle bombardment (2.2–8.2 MeV) have been determined from the experimental data and the currently available radiative transition probabilities, fluorescence yields, and Coster-Kronig factors. The measured ionization cross sections and their ratios are compared with the results of ECPSSR calculations [ECPSSR denotes perturbed-stationary-state (PSS) theory with energy-loss (E), Coulomb deflection (C), and relativistic (R) corrections]. The measured individual cross sections for ${\mathit{L}}_1$ and ${\mathit{L}}_2$ subshells deviated in opposite directions from the theory, whereas their sum shows good agreement. The ${\mathit{L}}_3$ and total ionization cross sections obtained from the data also show good agreement with the ECPSSR theory. The ionization cross-section ratios ${\mathrm{\sigma }}_{\mathit{L}1}$/${\mathrm{\sigma }}_{\mathit{L}2}$ and ${\mathrm{\sigma }}_{\mathit{L}3}$/${\mathrm{\sigma }}_{\mathit{L}2}$ show large deviations from the ECPSSR theory. The experimental x-ray production cross-section ratios are found to be in better agreement with the theoretical results obtained from using ECPSSR ionization cross sections and the decay yield data of Xu and Xu [J. Phys. B 25, 695 (1992)] rather than those obtained from using the decay yield data of Krause [J. Phys. Chem. Ref. Data 8, 307 (1979)]. The x-ray production cross sections, however, are in better agreement with the theoretical results obtained from using the decay yield data of Krause. The measured centroid energy of the Lγ lines of Pb shows large deviations at high projectile energy, whereas for Bi large deviations are found at the low-energy region.