The single-particle approach to the problem of C2 fragmentation of fullerene ions С60q+ (q = 1, 2, 3) by electron impact


Background. Experiments on the C2 fragmentation of fullerene ions C60q+ (q = 1, 2, 3), which is induced by electron impact, indicate the presence of two different mechanisms of these processes: plasmon excitation (at low energies of the incident electron) and ionization processes (at higher energies). At this one of the two free electrons recombine with of fullerene molecule. The aim of this paper is the examine the possibility of explaining the C2 fragmentation of fullerene ions C60q+ by electron impact in the framework of "oneparticle" approach, based on the study of e − C scattering processes.
Methods. The atomic structure and the excitation cross sections of e − C obtained by the B-spline R-matrix method. The close coupling expansion includes 28 spectroscopic states of carbon atoms, composed from 1s22s22p2, 1s22s22p3l (l = 1, 2, 3), 1s22s22p4s, 1s22s2p3, 1s22p4 configurations, and 8 pseudo-state. The cross sections of 2s and 2p ionization and 2p double ionization of an C atom was calculated by the Lotz formula.
Results. We determine the excitation total cross sections from four lower 2s22p2 3P, 1D, 1S, and 2s2p3 5S states of carbon atoms on the all overlying states. It is shown that the sum of cross sections the total excitation (σEX) and the ionization of 2s22p2 configurational shell (σDI) depends little on the final term of this shell. The excitation of the 2s2p3 5S metastable state is strongly suppressed. Comparison of the total cross sections of e−C collision with the C2 fragmentation cross sections indicates that they are differentiated to each other both on the structure of the energy dependence, as and in magnitude.
Conclusions. It is suggested that under the "oneparticle" approach to the problem of C2 fragmentation of the C60q+ fullerene ions should be taken as the basis the sp3-hybridizational states of 2s2p3 configuration of each of the two carbon atoms forming of molecule C2. It is also necessary to consider the possibility of re-scattering of free electrons

Keywords: C2 fragmentation, fullerene ions C60q+, the carbon atom, electron scattering, the B-spline R-matrix method, scattering cross sections