L -subshell x-ray cross sections for proton collisions with Pt, Au, and Hg

The L x-ray production cross sections for the Lα1,2, Lγ1,5, and Lγ2,3,6 transitions in Pt, Au, and Hg have been measured by ionization of the L-subshell electrons with 0.4-2.0-MeV proton bombardment. Individual subshell ionization cross sections, σ_Lᵢ(i=1, 2, or 3), have been extracted from the x-ray yields. Comparisons of the x-ray production and ionization cross-section data have been made with the predictions of the plane-wave Born approximation (PWBA), the PWBA with binding-energy and/or Coulomb-deflection effects, and the constrained binary-encounter approximation (CBEA). The binding-energy and Coulomb-deflection effects partially account for the gross quantitative discrepancies between the PWBA and the data for proton energies less than 1 MeV. Substantial discrepancy still exists, as evidenced by the disagreement between the data for σ_L₃σ_L₂ and all the theoretical predictions.