Reaction blockading in charged-neutral excited-state chemistry at low collision energy

Abstract

We study an excited atom-polar molecular ion chemical reaction (Ca${}^{\ast }$ + BaCl${}^{+}$) at low temperature by utilizing a hybrid atom-ion trapping system. The reaction rate and product branching fractions are measured and compared to model calculations as a function of both atomic quantum state and collision energy. At the lowest collision energy we find that the chemical dynamics dramatically differ from capture theory predictions and are primarily dictated by the radiative lifetime of the atomic quantum state instead of the underlying excited-state interaction potential. We provide a simple rule for calculating at what temperature this regime, where the collision complex lifetime is longer than the radiative lifetime of the quantum state, is reached. This effect, which greatly suppresses the reactivity of short-lived excited states, provides a means for directly probing reaction range. It also naturally suppresses unwanted chemical reactions in hybrid trapping experiments, allowing longer molecular ion coherence and interrogation times.

13 pages, 5 figures

References in corpus (6)

• A trapped single ion inside a Bose-Einstein condensate
• Controlling chemical reactions of a single particle
• Cold heteronuclear atom-ion collisions
• Synthesis of mixed hypermetallic oxide BaOCa${}^{+}$ from laser-cooled reagents in an atom-ion hybrid trap
• Sympathetic cooling of molecular ion motion to the ground state
• Blue-sky bifurcation of ion energies and the limits of neutral-gas sympathetic cooling of trapped ions

Cited by in corpus (13)

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• High-energy-resolution measurement of ultracold atom-ion collisional cross section
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• Reactions of Acetonitrile with Trapped, Translationally Cold Acetylene Cations
• Rotational state-changing collisions between N${}_2^{+}$ and Rb at low energies
• Photon-mediated charge-exchange reactions between 39K atoms and 40Ca+ ions in a hybrid trap
• Opposite effects of the rotational and translational energy on the rates of ion-molecule reactions near $0\text{K}$: the ${\text{D}}_2^{+}+{\text{NH}}_3$ and ${\text{D}}_2^{+}+{\text{ND}}_3$ reactions
• Fermi polaron in atom-ion hybrid systems
• Charge Exchange Dynamics in Cold Collisions of ${}^{40}$CaH${}^{+}$ and ${}^{39}$K
• Electric field dissociation of weakly bound molecular ions