Total and single differential cross sections for elemon impan ionization of helium are calculated within the R-mabix method. In addition to ionimlion of ground state &oms He (ls*) 'S, we consider the initial metastable states He (1~2s) 'S and He (IsZs) 'S for incident projectile energies ranging from threshold to 350 e?J Our dculalions include the processes which leave the residual ion in an excited state He+(nl) up to n = 3. The results are compared with experiments and other theoretical data.

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We present a theoretical study of electron-impact single ionization of Ne7+(1s22s 2S) using a formulation in which the incident/scattered electron is described by distorted waves, while the final continuum states of Ne7+ are calculated by the R-matrix method, thereby incorporating the excitation-autoionization process. With nine states of the residual Ne8+ included, we have calculated single-differential and total cross sections for impact energies from the threshold energy at 8.8-80 au. The single-differential cross sections exhibit considerable structure due to autoionizing resonances, dominated by the 1s2ℓ2ℓ' states. Our calculated total cross section is in good agreement with the available experimental data and with theoretical values obtained by a close-coupling calculation. Total cross sections for ionization in which the Ne8+ is left in the 1s2s 1,3S or 1s2p 1,3Po excited states are also presented.