Ion-loss events in a hybrid trap of cold Rb-Ca+ : Photodissociation, blackbody radiation, and nonradiative charge exchange

We theoretically investigate the collisional dynamics of laser-cooled 87Rb ground-state atoms and 40Ca+ ground-state ions in the context of the hybrid trap experiment of Hall et al. [Phys. Rev. Lett. 107, 243202 (2011)], leading to ion losses. Cold 87Rb40Ca+ ground-state molecular ions are created by radiative association, and we demonstrate that they are protected against photodissociation by blackbody radiation and by the 40Ca+ cooling laser at 397 nm. This paper yields an interpretation of the direct observation of 87Rb40Ca+ ions in the experiment, in contrast to other hybrid trap experiments using other species. Based on an updated model for molecular spin-orbit interaction, we also confirm that the nonradiative charge-exchange is the dominant loss process for Ca+ and obtain rates in agreement with experimental observations and a previous calculation.