Symmetric resonant charge transfer in H++H and He2++He collisions at extremely low energies.

Abstract

Symmetric resonant charge transfer (RCT) in ${\mathrm{H}}^{+}$+H and ${\mathrm{He}}^{2+}$+He collisions has been investigated in the ultralow-collision-energy range ${10}^{\mathrm{\ensuremath{-}}3}$--${10}^{\mathrm{\ensuremath{-}}7}$ eV. The RCT cross section has been computed by partial-wave expansion in the molecular-orbital expansion method within the fully quantum-mechanical formalism. The calculated RCT cross sections become constant below E\ensuremath{\simeq}${10}^{\mathrm{\ensuremath{-}}6}$ eV, corresponding to a scattering length of \ensuremath{\sim}6${a}_{0}$ and \ensuremath{\sim}2${a}_{0}$ for ${\mathrm{H}}_{2}$${\mathrm{}}^{+}$ and ${\mathrm{He}}_{2}$${\mathrm{}}^{2+}$, respectively.