ELECTRON-CAPTURE AND DISSOCIATION OF THE N-2(Q+) MOLECULE IN SLOW AR8+ N-2 COLLISIONS/

Single and multiple electron capture processes are studied in slow (8- 16 keV) collisions between Ar8+ and molecular nitrogen. The contributi ons of dissociative and nondissociative channels are determined as wel l as the kinetic energies of the fragments of the N-2(q+) (q = 1-6) io ns. From the kinetic energies of the fragments dissociation energies o f the N-2(q+) molecular ion are deduced.Under the assumption of isotro pic dissociation the following results are obtained: at most 7% of sin gle-electron capture leads to dissociation of N-2(+) into N + N+ and a t least 90% of the double-electron capture results in fragmentation in to N+ + N+. If more than two electrons are captured, all N-2(q+) -ions dissociate into N-r+ + N-s+. For even values of q we observe r = s, o therwise r = s +/- 1; i.e. the maximum difference between r and s is 1 . A charge distribution closest to the most symmetric one is preferred . The measured dissociation energies are smaller than those expected f rom the model of Coulomb explosion. Therefore, potential curves for th e N-2(4+) and N-2(6+) molecular ions have been calculated, and dissoci ation energies deduced from these potential curves have been compared to the measured ones. In both cases dissociation from the lowest molec ular state of the multicharged molecule seems most probable.