Interference of direct and resonant channels in electron-impact ionization of C³⁺ ions: Unified R-matrix calculation and experiment

Calculated total cross sections for electron-impact ionization of C³⁺ using a unified theoretical approach are compared with high-resolution high-precision measurements clearly demonstrating interference of resonant multielectron reaction channels with direct ionization and inner-shell excitation. In particular, the so-called READI process, i.e., K-shell excitation with simultaneous capture of the incident electron (resonant-excitation) and a subsequent three-electron interaction resulting in simultaneous ejection of two electrons (auto-double-ionization) has been studied in unprecedented detail. The calculation is in very good agreement with the experimental cross section.