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arXiv · 2602.09142

Charge Exchange Dynamics in Cold Collisions of $^{40}$CaH$^+$ and $^{39}$K

Swapnil Patel·Dibyendu Sardar·Jyothi Saraladevi·Michał Tomza·Kenneth R. Brown
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Abstract

We report the observation of charge-exchange collisions between trapped calcium monohydride molecular ions ($^{40}$CaH$^+$) and ultracold potassium atoms ($^{39}$K) in a hybrid ion-atom trap. The measured charge-exchange rate coefficient is significantly suppressed relative to the Langevin rate constant for the system. We use $\mathit{ab\ initio}$ quantum-chemical calculations to model the (CaH-K)$^+$ complex in the ground and excited electronic states and to identify possible charge-exchange mechanisms. Our calculations rule out a direct non-radiative charge-exchange reaction and instead point to a radiative mechanism, but do not quantitatively reproduce the measured rate, highlighting the need for a full-dimensional quantum dynamics treatment that includes vibrational motion and intermediate complex formation. Our work demonstrates that cold hybrid ion-atom platforms with molecular ions enable access to richer chemical complexity and collisional dynamics inaccessible in purely atomic systems.

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Swapnil Patel, Dibyendu Sardar, Jyothi Saraladevi, Michał Tomza, Kenneth R. Brown. 2026-02-09. Charge Exchange Dynamics in Cold Collisions of $^{40}$CaH$^+$ and $^{39}$K. https://doi.org/10.1021/acs.jpclett.6c00828

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