Indirect processes in electron-impact ionization of Li+

The first detailed result is reported for the contribution of indirect processes in electron-impact ionization of Li+ ions in the energy range 132-168 eV using a unified theoretical treatment based on the R-matrix method. Eleven bound target states, ten pseudo states, together with 26 autoionizing states, a total of 47 states, are explicitly included in the R -matrix expansion to describe both direct and indirect processes as well as interaction between them. The calculated resonance features due to double-excitation autoionization, resonant double-excitation double-autoionization and resonant double-excitation auto-double-ionization are in very good agreement with the experimental results of Mueller et al (Mueller A et al 1989 Phys. Rev. Lett. 63 758). (author). Letter-to-the-editor