Abstract
The investigation of cold interactions between ions and neutrals has recently emerged as a new scientific frontier at the interface of physics and chemistry. Here, we report a study of charge-transfer (CT) collisions of Rb atoms with N{}_{2}^{+} and O{}_{2}^{+} ions in the mK regime using a dynamic ion-neutral hybrid trapping experiment. We observe markedly different CT kinetics and dynamics for the different systems and reaction channels studied. While the kinetics in some channels are consistent with classical capture theory, others show distinct non-universal dynamics. The experimental results are interpreted with the help of classical-capture, quasiclassical-trajectory and quantum-scattering calculations using ab-initio potentials for the highly excited molecular states involved. The theoretical analysis reveals an intricate interplay between short- and long-range effects in the different reaction channels which ultimately determines the CT dynamics and rates. Our results illustrate salient mechanisms that determine the efficiency of cold molecular CT reactions.
Highlights
The investigation of cold interactions between ions and neutrals has recently emerged as a new scientific frontier at the interface of physics and chemistry
We explore this topic here in a comparative study of the CT between molecular oxygen (32Oþ2 ) and nitrogen (28Nþ2 ) ions with 87Rb atoms using experiments in the cold regime together with computational work to interpret the dynamics at a molecular level
The experiments were conducted in an ion-neutral hybrid trapping experiment consisting of a linear radiofrequency ion trap embedded in a magneto-optical trap (MOT) for Rb atoms (Methods)[7,30]
Summary
The investigation of cold interactions between ions and neutrals has recently emerged as a new scientific frontier at the interface of physics and chemistry. Previous experiments, included the combination of cold molecular beams or cryogenic gases with trapped ions[19,20], the merging of molecular beams containing Rydberg molecules[21], and the sympathetic cooling of molecular ions in hybrid trapping experiments[13,22,23,24] These latter studies uncovered unusually fast kinetics[22], the formation of exotic molecular species[23] and reaction blockading of short-lived excited species[24] in cold molecular ion-neutral atom systems. These investigations gave a first glimpse at the wealth of additional phenomena which can be explored by extending hybrid trapping experiments from atomic to molecular systems. We explore this topic here in a comparative study of the CT between molecular oxygen (32Oþ2 ) and nitrogen (28Nþ2 ) ions with 87Rb atoms using experiments in the cold regime together with computational work to interpret the dynamics at a molecular level
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