Asymmetrical fission of C 60 rϩ (rϭ4 -9) ions are studied in Xe 25ϩ -C 60 collisions at 100 keV impact energy (vϷ0.18 a.u.). The branching ratios for the emission of a singly or a doubly charged light fragment, C m ϩ or C m 2ϩ , are measured for each initial charge state r. The measured m-dependent branching ratios for the singly charged C m ϩ fragment emission channels are reproduced using a simple statistical model. The ionization energies I(C 60Ϫ2n qϩ ) for even numbered fullerenes C 60Ϫ2n qϩ (qϭ1 -5, 8; nϭ1 -4) and I(C 2n ϩ ) for singly charged light fragments C 2n ϩ (nϭ1 -4) are estimated by the density-functional theory. The total branching ratio for the C m 2ϩ emission channels is found to increase from less than 2 to 25% when the charge r of the parent ion C 60 rϩ increases from 5 to 9.

We have studied the excitation and dissociation processes of the molecule W(CO)(6) in collisions with low kinetic energy (3 keV) protons, monocharged fluorine, and chlorine ions using double charge transfer spectroscopy. By analyzing the kinetic energy loss of the projectile anions, we measured the excitation energy distribution of the produced transient dications W(CO)(6)(2+). By coincidence measurements between the anions and the stable or fragments of W(CO)(6)(2+), we determined the energy distribution for each dissociation channel. Based on the experimental data, the emission of the first CO was tentatively attributed to a nonstatistical direct dissociation process and the emission of the second or more CO ligands was attributed to the statistical dissociation processes. The dissociation energies for the successive breaking of the W-CO bond were estimated using a cascade model. The ratio between charge separation and evaporation (by the loss of CO(+) and CO, respectively) channels was estimated to be 6% in the case of Cl(+) impact.