Charge transfer in collisions of doubly charged ions of iron and nickel with hydrogen atoms.

Abstract

The Landau-Zener approximation is used to compute the charge-transfer recombination rate coefficients of ${\mathrm{Fe}}^{2+}$ and ${\mathrm{Ni}}^{2+}$ in hydrogen at thermal energies. The energy separations of the adiabatic potential-energy curves of the quasimolecules ${\mathrm{FeH}}^{2+}$ and ${\mathrm{NiH}}^{2+}$ are obtained from one-electron calculations. The rate coefficients are of the order of ${10}^{\mathrm{\ensuremath{-}}9}$ ${\mathrm{cm}}^{3}$? sup -1--- or greater. Charge transfer of ${\mathrm{Fe}}^{2+}$ occurs preferentially into the ground state of ${\mathrm{Fe}}^{+}$ so that the reverse process of charge-transfer ionization of ${\mathrm{Fe}}^{+}$ in collision with ${\mathrm{H}}^{+}$ also occurs rapidly above the reaction threshold.