L-SUBSHELL IONIZATION STUDIES IN AU AND BI FOR F-19 AND SI-28 LARGE-ION BOMBARDMENT

L x-ray production and subshell ionization cross sections of Au and Bi have been measured for the bombardment of F-19 and Si-28 ions in the energy range 30-57 MeV and 36-84 MeV, respectively. Comparison of the L alpha x-ray production cross sections of Au with the earlier data by Malhi and Gray [Phys. Rev. A 44, 7199 (1991)] shows reasonable agreem ent for F-19 impact and their data are consistently higher for Si-28 a t all energies. The measured L alpha line energy shows a shift towards higher energy, which appears to be proportional to the square of the projectile atomic number at all impact energies. This shift suggests t he presence of multiple ionization in the L and M shells with a simult aneous production of four M holes in Au at the impact energy of 3 MeV u(-1) of Si-28. The L-subshell ionization cross sections obtained from the measured x-ray production cross sections have been compared with the semiclassical approximation and perturbed stationary state theory with energy loss. Coulomb deflection, and relativistic correction for the electron motion calculations, which show large deviations for the L(1) subshell. The L(2) and L(3)-subshell ionization cross sections ar e underestimated by both the theories by a factor of 1.2-4.0 for Si-28 impact whereas for the F-19 case there is reasonable agreement for th e L(3) cross section but the L(2) cross section is underestimated by 2 0-30%.