Charge exchange in tandem mass spectrometry: dissociative single electron capture by doubly-charged toluene cations.

Single electron capture by doubly-charged toluene cations upon collision with various target gases has been investigated by sector tandem mass spectrometry. Both non-dissociative and dissociative charge transfer reactions leading to C7H7+ + H and to C5H5+ + [C2,H3] are detected. Seven atomic or molecular target gases have been used with ionisation energies ranging from 8.8 eV to 14 eV. The branching ratios between the different non-dissociative and dissociative exit channels have been determined as well as the translational energy release on the dissociation products. The experimental data are compared to the predictions of a two-state semi-classical theoretical model that takes into account the non-adiabatic transition responsible for the charge transfer reaction. A wide reaction window shows up but the internal energies of the C7H8+ cations produced by single electron capture are observed to be larger than expected. We assign this effect partly to the influence of the large density of vibrational states...