Role of two-electron processes in the excitation-ionization of lithium atoms by fast ion impact

摘要

We study excitation and ionization in the 1.5 MeV/amu O$^{8+}$-Li collisionsystem, which was the subject of a recent reaction-microscope-type experiment[Fischer \textit{et al.}, Phys. Rev. Lett. \textbf{109}, 113202 (2012)].Starting from an independent-electron model based on determinantal wavefunctions and using single-electron basis generator method and continuumdistorted-wave with eikonal initial-state calculations we show that pure singleionization of a lithium $K$-shell electron is too weak a process to explain themeasured single differential cross section. Rather, our analysis suggests thattwo-electron excitation-ionization processes occur and have to be taken intoaccount when comparing with the data. Good agreement is obtained only if wereplace the independent-electron calculation by an independent-event model forone of the excitation-ionization processes and also take a shake-off processinto account.