Structure and charge transfer dynamics of the (Ar-N2)+ molecular cluster

In this paper we have investigated the interaction potential and the charge transfer processes at low collision energies in the (Ar-N-2)(+) system. The angular dependence of the lowest doublet potential energy surfaces (PES), correlating with Ar+(P-2(j))-N-2 and Ar-N-2(+)((2)Sigma,(2)Pi), has been given in terms of spherical harmonics, while the dependence on the intermolecular distance has been represented by proper radial coefficients. Such coefficients, which account for van der Waals, induction, charge transfer, and electrostatic contributions, have been predicted by empirical correlation formulas. The PES so obtained have been employed to calculate cross sections for the charge transfer process Ar++N-2--> Ar+N-2(+) at low collision energy (E less than or equal to2 eV). A good agreement between calculated and experimental cross sections is obtained by assuming that the duration of the nonadiabatic transition has to match the time required for the molecular rearrangement into the final vibrational state. As a consequence the efficient formation of product ions into specific vibrational states is limited to well defined ranges of impact parameters. This treatment leads to a unified description of the major experimental findings. (C) 2001 American Institute of Physics.