Electron-impact ionization of W9+ and W10+

Electron-impact single-ionization (EISI) cross sections for W q+ (q = 9, 10) ions have been calculated by using the level-to-level distorted-wave (LLDW) method with emphasis on the contribution of metastable states to the total ionization cross sections. Contributions from direct-ionization (DI) and excitation-autoionization (EA) processes are taken into account. The calculated cross sections include the contributions from both the ground configuration and the long-lived metastable states with lifetimes exceeding 10(-6) s. Calculated cross sections are in good agreement with experimental measurements when the influence of metastable states on the total ionization cross section are well considered.