Charge exchange in the O⁸⁺-He collision at keV amu^-1energies

Abstract

Charge exchange between O8+ and He(1s2) is studied both theoretically and experimentally. In the energy range where capture cross sections have been measured good agreement is obtained between theory and experiments. Calculations predict that in single-electron capture the electron is transferred dominantly into O7+ (n=4), which is supported by earlier experimental work.

Partial autoionisation widths of2S+1Lodoubly excited O6+states associated with N = 3 and 4, O7+threshold

“…Our results are in good agreement with those obtained by Ivanov and Safronova for the partial width decay of (3s3p) 3 P°and (3p3d) 3 P°and are in fairly good agreement with the partial width decay of (3s3p) 1 P°reported in table 1. There is a notable discrepancy with the total width calculated by Ivanov and Safronova for the (3p3d) 3 D°decay reported in table 2.…”

“…The comparison of our partial width calculations of the 3l3l′ and 4l4l′ singlet states with that of Chetoui et al indicates a satisfactory agreement for the 1,3 P°states. The discrepancies noticed with the partial width decay of (4s4p) 1 P°t o 1s seems to come in the reporting value since all of the other decay partial widths are close to ours.…”

“…In the last two decades, interest in experimental [1][2][3][4][5][6] and theoretical studies of resonant photoionization of helium-like ions and the properties of autoionizing states has been renewed by the advent of high-energy resolution spectrometers using synchrotron radiation and the appearance of multiply charged ions sources such as electron cyclotron resonance or an electron-beam ion source. Doubly excited states in He-like ions have been intensively studied in connection with the understanding of collisional and radiational processes, which take place in hot astrophysical and laboratory plasmas.…”

Multiphoton ionization of one-electron diatomic molecules: the discretization approach for the two-centre problem

“…It has been shown to be very efficient for systems involving heavy ions and large internuclear distances. The earlier applications concern close-coupling calculations for one-and two-electron capture, they involve bound or quasi-bound states (see for example Harel andSalin 1977, Bliman et al 1983), an invaluable number of works has followed and the list is certainly far from being closed. The study of multiphoton ionization of molecular systems requires the representation of both the bound and continuum spectra.…”

On the calculation of doubly excited states

“…The perturber states have a clear physical meaning in the collisional context; they are first populated through a double-electron capture process during the collision (Bliman et al 1983, Bárány et al 1985, Niehaus 1986), then they interact with the (3, n) Rydberg series and 2lkl and 1skl continua in the way out of the collision. The post-collisional interaction with Rydberg series can be interpreted as a decay to (3, n) states (Bachau et al 1992(Bachau et al , 1993, while the interaction with the continua induces autoionizing widths.…”