EXPERIMENTAL-EVIDENCE IN FAVOR OF THE STARK MIXING OF ATOMIC L-SUBSHELL STATES IN THE BORON IMPACT OF AU AND BI

L-subshell ionization of Au and Bi induced by boron impact has been in vestigated for impact energies ranging from 0.48 to 0.88 MeV/u. The en ergy dependence of the measured ionization cross section shows, for th e first time, a plateau structure for all three subshells. The plateau structure revealed by previous data for proton and helium impact was for the L(1) subshell only and this had been attributed to the bimodal nature of the 2s electron density. The observed plateau structure for all the three subshells and its occurrence at a somewhat lower energy signifies a considerable amount of Stark mixing of target 2s and 2p a tomic wavefunctions. Fresh calculations incorporating the Stark mixing effect in target atomic wavefunctions are necessary to improve agreem ent with the present data. The existing theories, however, are found t o be inadequate.