Hydrogen migration plays an important role in the chemistry of hydrocarbons which considerably influences their chemical functions. The migration of one or more hydrogen atoms occurring in hydrocarbon cations has an opportunity to produce the simplest polyatomic molecule, i.e. H3+. Here we present a combined experimental and theoretical study of H3+ formation dynamics from ethane dication. The experiment is performed by 300 eV electron impact ionization of ethane and a pronounced yield of H3+ + C2H3+ coincidence channel is observed. The quantum chemistry calculations show that the H3+ formation channel can be opened on the ground-state potential energy surface of ethane dication via transition state and roaming mechanisms. The ab initio molecular dynamics simulation shows that the H3+ can be generated in a wide time range from 70 to 500 fs. Qualitatively, the trajectories of the fast dissociation follow the intrinsic reaction coordinate predicted by the conventional transition state theory. The roaming mechanism, compared to the transition state, occurs within a much longer timescale accompanied by nuclear motion of larger amplitude.

The absolute electron capture cross sections for single and double charge exchanges (CEs) between the highly charged ion O6+ and CO2, CH4, H2, and N2, the dominant collision processes in the solar wind, have been measured in the energies from 7 keV · q (2.63 keV u−1) to 52 keV · q (19.5 keV u−1). These measurements were carried out in the new experimental instrument setup at Fudan University, and the errors of the cross sections for single and double CEs at the 1σ confidence level were about 11% and 16%, respectively. Limited agreement is achieved with single electron capture results calculated by the classical overbarrier model. These cross section data are useful for the simulation of ion–neutral processes in astrophysical environments and to improve the present theoretical model of fundamental atomic processes.

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