Electron-impact Cross Sections And Ionization Rate Coefficients Of Heavy Ions

It is very significant to investigate electron-heavy ion impact both in theory and practice. Electron impact elastic scattering, direct ionization(single or multiple), excitation and resonant recombination can take place during the processes, accompanying with which autoionization and radiative transition can take place at the same time. Different value ions can be generated from different process, and the same value ions can be contributed by different processes.Electron-impact direct single and multiple ionizations are among the most important basic atomic processes. A pair of slow-fast electrons can be scattered after collision of a high energy electron with an ion, while the probability of two equal electrons are quite smaller. By investigating singly differential cross-section of H and He, we find that there is a big singly differential cross section at both low and high scatting electron energy,which correspond to low and fast electrons, while at the medium energy the singly differential cross-section is quite small. We investigated the excitation, ionization and double ionization of heavy ions by including all possible channels, taking Sn13+as an example. We especially studied the effects of single and double ionization branching ratios on cross sections and the contributions of resonant excitation double autoionization to single ionization. A comparison with Brovik Jr. A. showed that accurate determination of the branching ratios of single and double ionization and including contributions of the resonant excitation double autoionization(REDA) are crucial to obtain accurate results. We also investigated the contributions of REDA processes to Xe25+—Xe18+ electron-impact single ionization(EISI) cross sections and rate coefficients, which reveal the contributions of REDA processes to EISI cross sections are over 50% at resonant energy, and the contributions to EISI rate coefficients are between 5%—10%. We also preliminarily investigated Electron-impact direct double ionization by perturbation theory. We investigated the direct double ionization cross sections of C+, N+, O+, F+and Ne+, and the error divergences between our calculations with the experiments are less than 25%..