Light-assisted cold chemical reactions of barium ions with rubidium atoms

Abstract

Light-assisted reactive collisions between laser-cooled Ba + ions and Rb atoms were studied in an ion-atom hybrid trap. The reaction rate was found to strongly depend on the electronic state of the reaction partners with the largest rate constant (7(2) × 10 −11 cm 3 s −1 ) obtained for the excited Ba + (6s)+Rb(5p) reaction channel. Similar to the previously studied Ca + +Rb system, charge transfer and radiative association were found to be the dominant reactive processes. The generation of molecular ions by radiative association could directly be observed by their sympathetic cooling into a Coulomb crystal. Potential energy curves up to the Ba + (6s)+Rb(5p) asymptote and reactive-scattering cross sections for the radiative processes were calculated. The theoretical rate constant obtained for the lowest reaction channel Ba + (6s)+Rb(5s) is compatible with the experimental estimates obtained thus far. * Electronic address: stefan.willitsch@unibas.ch arXiv:1301.0724v1 [physics.atom-ph]

Perspective: Ultracold molecules and the dawn of cold controlled chemistry

“…A highly efficient charge transfer that depends on the internal state of the Rb atom was observed, with a rate that is four times larger than the Langevin rate, for Rb in the excited (5p) 2 P 3/2 state. Reactions of laser-cooled Rb atoms and Ba + ions were also reported by Hall et al 119 Chang et al 60 recently extended this technique to study conformational effects in chemical reactions by investigating reactions of spatially separated 3-aminophenol with cold Ca + ions. Spatial separation of conformers was achieved through electrostatic deflection of the molecular beam.…”

“…[117][118][119] Cold reactive ion-molecule collisions are also of considerable interest. 59,118 In this case, spatially ordered laser-cooled ions ("Coulomb crystals") react with cold molecules from a quadrupole-guide velocity selector.…”

Characterization of charge-exchange collisions between ultracold Li6 atoms and Ca40+ ions

“…In contrast to heavier systems like RbCa + and RbBa + [7,8,19], the LiCa + species is light enough to allow accessing to the PECs up to Li(2s) + Ca + (4p), thus representing an appealing species to sort out the complicated dynamics taking place in such a hybrid trap. Assuming that only two-body reactions are expected in the present experimental conditions, one can immediately infer several statements allowing us to understand the present experimental results.…”

Design and characterization of a linear quadrupole ion trap for high-resolution Coulomb-crystal time-of-flight mass spectrometry

“…Cold, trapped ions are of interest for a variety of topics, ranging from precision spectroscopy [1] and quantum information [2] to the dynamics of ion-molecule reactions [3][4][5]. Laser-and sympathetically-cooled ions in traps form ordered structures termed Coulomb crystals [6].…”