Resonant and non-resonant charge transfer in and collisions

Abstract

Charge transfer cross sections σ CT were measured for the single-electron charge transfer reactions C + 60/70 + C 60 → C 60/70 + C + 60 + E as a function of the collision energy E in the range 200-2100 eV. For both processes the absolute values of the cross sections are similar to the geometrical cross sections and decrease with increasing collision energy below E = 400 eV.In the case of C + 60 projectiles, the charge transfer cross section remains almost constant for larger collision energies while σ CT increases in the case of capture by C + 70 beyond 400 eV and saturates around 1350 eV. From an interpretation of the measured cross sections using very simple models it can be concluded that the electron transfer is resonant in collisions between C + 60 and C 60 , as would be expected, and has both resonant and non-resonant contributions for C + 70 projectiles. The qualitative agreement of the experimental results with very simple oneelectron models developed to describe the general trends of the charge transfer cross sections determined in ion-atom collisions in the intermediate energy range (where the semiclassical impact parameter method can be applied) is quite surprising.

Resonant Electron Transfer in Collisions between Two Fullerene Ions

“…Most surprisingly, the measured cross sections virtually coincide with the data by Rohmund et al [7] for the reaction C 60 C 60 ! C 60 C 60 at much lower collision energies between 0.5 and 1.9 keV (Fig.…”

“…We further present a quantum treatment expanding on this model, which also reproduces very well the experimental data for the reaction C 60 C 60 ! C 60 C 60 at much lower collision energies [7].…”

“…We therefore analyze our experimental data for resonant electron transfer between singly and doubly charged fullerene ions, C 60 C 2 60 , jointly with those [7] for collisions of singly charged ones with neutral fullerenes, C 60 C 60 . For both processes, we use the same model in which we consider the positively charged fullerene ions in a collision as cages with well-defined positive charges that can move freely over the surface [4,11].…”

Molecular fusion of fullerenes

“…In our laboratory we have been studying fullerene-fullerene collisions in the intermediate collision energy regime (50-5000 eV) where a number of competing reaction channels occur: scattering [2], fusion [3][4][5], evaporation, (multi-)fragmentation [4] and charge transfer [2,6]. The fusion reaction channel is particularly interesting since there are many similarities but also some important differences compared to the dynamics of nuclear collisions [7].…”

“…The fusion reaction channel is particularly interesting since there are many similarities but also some important differences compared to the dynamics of nuclear collisions [7]. Our early experiments considered only the reaction products within a small scattering angle range about 0 • [7,6]. The more recent work has concentrated on the scattering angle dependence of the fragmentation [4] and charge transfer [2] products and is able to provide considerable insight into the collision dynamics as well as to confirm the earlier interpretations in terms of simple models.…”