Structure and charge transfer dynamics of the (Ar-N-2)(+) 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. Th e 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 g iven in terms of spherical harmonics, while the dependence on the intermole cular distance has been represented by proper radial coefficients. Such coe fficients, 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 section s for the charge transfer process Ar++N-2--> Ar+N-2(+) at low collision ene rgy (E less than or equal to2 eV). A good agreement between calculated and experimental cross sections is obtained by assuming that the duration of th e nonadiabatic transition has to match the time required for the molecular rearrangement into the final vibrational state. As a consequence the effici ent formation of product ions into specific vibrational states is limited t o well defined ranges of impact parameters. This treatment leads to a unifi ed description of the major experimental findings. (C) 2001 American Instit ute of Physics.