Double Rotational Rainbows in Collisions of Homonuclear Diatoms Stemming from Steric Charge Transfer

), using an advanced imaging-based ion-molecule crossed-beam method. Trajectory surface hopping calculations involving multiple electronic states reproduced the experimental observations qualitatively and revealed that collinear approaches of the two colliders show higher charge-transfer efficiencies than side-on approaches due to angle-dependent nonadiabatic interactions. The closest encounters before and after charge transfer experience vastly different anisotropies of the short-range intermolecular repulsion in the two charge-transfer states, thus manifesting as the twin rainbow structures. This mechanism differs fundamentally from those observed in the adiabatic scattering.