Measurement of charge exchange between Na and Ca+ in a hybrid trap

Abstract

We present measurements of the charge-exchange reaction rate between neutral sodium (Na) and ionized calcium (${\mathrm{Ca}}^{+}$) in a hybrid atom-ion trap, which is comprised of a Na magneto-optical trap concentric with a linear Paul trap. Once the Na and ${\mathrm{Ca}}^{+}$ are co-trapped, the reaction rate is measured by continuously quenching the reaction product ${\mathrm{Na}}^{+}$ from the ion trap, and then destructively measuring the decay of the remaining ion population. The reactants' electronic state and temperature are experimentally controlled, allowing us to determine the four individual reaction rates between $\text{Na}[S\phantom{\rule{4.pt}{0ex}}\text{or}\phantom{\rule{4.pt}{0ex}}P]$ and ${\text{Ca}}^{+}[S\phantom{\rule{4.pt}{0ex}}\text{or}\phantom{\rule{4.pt}{0ex}}D]$ at different collision energies. With the exception of the largest reaction-rate channel ($\text{Na}[P]+{\text{Ca}}^{+}[D]$), our rates are consistent with the classical Langevin rate limit. We have also found evidence of reactant collision-energy thresholds associated with two of the four entrance channels.