Multielectron processes in 10-keV/u Arq+ (5

Abstract

We have used time-of-flight coincidence techniques to study multielectron reactions in 10-keV/u (v=0.632 a.u.) ${\mathrm{Ar}}^{\mathit{q}+}$ (5\ensuremath{\le}q\ensuremath{\le}17) on Ar collisions. Absolute cross sections for total charge-transfer (${\mathrm{\ensuremath{\sigma}}}_{\mathit{q}}$), projectile charge-change (${\mathrm{\ensuremath{\sigma}}}_{\mathit{q},}$${\mathit{q}}_{\mathrm{\ensuremath{-}}\mathit{k}}$), recoil production (${\mathrm{\ensuremath{\sigma}}}_{\mathit{q}}^{\mathit{i}}$), and phenomenological cross sections (${\mathrm{\ensuremath{\sigma}}}_{\mathit{q},}$${\mathit{q}}_{\mathrm{\ensuremath{-}}\mathit{k}}^{\mathit{i}}$) have been obtained by normalizing to cross sections reported in the literature [H. Klinger, A. M\"uller, and E. Salzborn, J. Phys. B 8, 230 (1975)]. The data have been used to critically test the predictions of the molecular classical overbarrier model (MCBM) [A. Niehaus, J. Phys. B 19, 2925 (1986)] and rather impressive agreements have been obtained. In particular, the predictions of target outer-shell excitation seem to have supporting evidence in this set of data. A stabilization scheme for the multiply excited projectile following charge transfer is proposed to complement the MCBM predictions and the gross features of the final reaction products are fairly accounted for. In addition, enhanced electron loss from the projectile-target system is observed in hard collisions for low-charged projectiles (q\ensuremath{\le}8) and is attributed to inner-shell excitation via molecular-orbital promotion.