We review the recent advances in the investigation of the dynamics of ion–molecule reactions. During the past decade, the combination of single-collision experiments in crossed ion and neutral beams with the velocity map ion imaging detection technique has enabled a wealth of studies on ion–molecule reactions. These methods, in combination with chemical dynamics simulations, have uncovered new and unexpected reaction mechanisms, such as the roundabout mechanism and the subtle influence of the leaving group in anion–molecule nucleophilic substitution reactions. For this important class of reactions, as well as for many fundamental cation–molecule reactions, the information obtained with crossed-beam imaging is discussed. The first steps toward understanding micro-solvation of ion–molecule reaction dynamics are presented. We conclude with the presentation of several interesting directions for future research.

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