Charge transfer inF2+ions colliding with He atoms below keV energies and its reverse process

Abstract

Charge transfer processes in collisions of ${\mathrm{F}}^{2+}$ ions with He atoms were studied by using the molecular representation below 600 eV energies. The ground ${\mathrm{F}}^{2+}{(}^{4}S)$ state and one excited ${\mathrm{F}}^{2+}{(}^{2}D)$ state are considered as the initial channels in order to examine the effect of the excited state. We have also investigated charge transfer processes in the reverse ion-ion collisions. Cross sections for nonradiative charge transfer in the ground quartet state ${\mathrm{F}}^{2+}+\mathrm{H}\mathrm{e}$ collisions are found to increase gradually with the impact energy and reach around $2\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}16}{\mathrm{cm}}^{2}$ at 558 eV, while those from the doublet state also show a gradual increase and stay nearly constant with $1.2\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}16}{\mathrm{cm}}^{2}$ at the same energy. Cross sections for the reverse processes for both symmetries are found to be very small with a magnitude less than ${10}^{\ensuremath{-}18}{\mathrm{cm}}^{2}$ due to the strong Coulomb repulsion between two ions, but rapidly increase as the collision energy increases to reach $3\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}17}$ and ${10}^{\ensuremath{-}17}{\mathrm{cm}}^{2}$ for the quartet and doublet manifolds, respectively, at the highest energy studied.