Sequential Synchronous Mechanism for Double-Electron Capture: Insights into Unforeseen Large Cross Sections in Low-Energy Sn3++H2 Collisions

Remarkably large double electron capture cross sections, on the scale of 10−15 cm2, are observed in low-energy (<50 eV/u) collisions between Sn3+ and H2. Given that the reaction is energetically highly unfavorable, one would expect negligibly small cross sections. Through the propagation of vibrational wave packets on coupled multiple potential energy surfaces, a novel charge transfer mechanism, driven in tandem by ion motion and molecular vibration, is revealed, offering insights into the unusual energy dependence of the measured cross sections. Published by the American Physical Society 2025