Study of the L -shell x rays of Ta, Pt, Au, Hg, and Pb by proton bombardment

The L x-ray transition ratios L(α₁₂l), L(γ₁η), L(ηγ₅), L(γ₂₃₆γ₁), and L(γ_44^'γ₁) have been measured for the elements ⁷³Ta, ⁷⁸Pt, ⁷⁹Au, ⁸⁰Hg, and ⁸²Pb by ionization of the L-subshell electrons with 0.4-2.0-MeV proton bombardment. Transition-rate ratios L(γ₂₃γ_44^') to the L₁ subshell, L(γ₆γ₁), L(γ₁η), and L(ηγ₅) to the L₂ subshell, and L(α₁₂l) to the L₃ subshell have been extracted. Comparison of the extracted ratios with the relativistic Hartree-Fock model calculations of Scofield shows agreement within experimental errors for the L₁, L₂, and L₃ subshell ratios. A previously reported minimum in the Pb L(α₁₂l) ratio between proton energies 1.0 to 1.5 MeV was not observed. Total L-shell production cross sections have also been measured for Pt and Au over the energy range 0.4-2.0 MeV and are found to be in good agreement with the predictions of the nonrelativistic plane-wave Born approximation and the constrained binary-encounter approximation, but not with the binary-encounter approximation.