State-resolved Mutual Neutralization of O+16 with H−1 and <…

We measured the product-state distribution and its dependence on the hydrogen isotope for the mutual neutralization between O+16 and H−1,2 at the double electrostatic ion-beam storage ring DESIREE for center-of-mass collision energies below 100 meV. We find at least six product channels into ground-state hydrogen and oxygen in different excited states. The majority of oxygen products populate terms corresponding to 2s22p3(4S∘)4s with S∘5 as the main reaction product. We also observe product channels into terms corresponding to 2s22p3(4S)3p. Collisions with the heavier hydrogen isotope yield a branching into these lower excited states smaller than collisions with H−1. The observed reaction products agree with the theoretical predictions. The detailed branching fractions, however, differ between the theoretical results, and none of them fully agree with the experiment. Published by the American Physical Society 2024