L subshell ionisation cross sections of Au and Bi by helium ions of energy 0.9 to 1.8 MeV

Abstract

L subshell ionisation cross sections for ⁴He ion impact on Au and Bi have been measured systematically in the energy range 0.9 to 1.8 MeV in steps of 0.1 MeV. Thin targets have been used in transmission geometry. Subshell ratios sigma 2s(1²)// sigma 2p(1²)/ and sigma 2p(3²)// sigma 2p(1²)/ have been obtained as a function of ⁴He ion energy. Data are compared with the theoretical predictions of the PWBA and PWBA with corrections due to Coulomb deflection of the projectile, increased binding of the target electron during collision and the relativistic nature of the target electrons. It appears that no single theoretical formulation gives overall agreement with data for all the three subshells.