Radiative charge transfer in ultracold collisions of Yb ions and Rb atoms

Charge-transfer cold Yb ${}^{+}$ $+$ Rb collision dynamics is investigated theoretically using high-level ab initio potential energy curves, dipole moment functions, and nonadiabatic coupling matrix elements. Within the scalar-relativistic approximation, the radiative transitions from the entrance $A{\phantom{\rule{0.16em}{0ex}}}^{1}{\ensuremath{\Sigma}}^{+}$ to the ground $X{\phantom{\rule{0.16em}{0ex}}}^{1}{\ensuremath{\Sigma}}^{+}$ state are found to be the only efficient charge-transfer pathway. The spin-orbit coupling does not open other efficient pathways, but alters the potential energy curves and the transition dipole moment for the $A\ensuremath{-}X$ pair of states. The radiative, as well as the nonradiative, charge-transfer cross sections calculated within the ${10}^{\ensuremath{-}3}--10$ cm${}^{\ensuremath{-}1}$ collision energy range exhibit all features of the Langevin ion-atom collision regime, including a rich structure associated with centrifugal barrier tunneling (orbiting) resonances. Theoretical rate coefficients for two Yb isotopes agree well with those measured by immersing Yb ${}^{+}$ ions in an ultracold Rb ensemble in a hybrid trap. Possible origins of discrepancy in the product distributions and relations to previously studied similar processes are discussed.Charge-transfer cold Yb${}^{+}$$+$ Rb collision dynamics is investigated theoretically using high-level ab initio potential energy curves, dipole moment functions, and nonadiabatic coupling matrix elements. Within the scalar-relativistic approximation, the radiative transitions from the entrance $A{\phantom{\rule{0.16em}{0ex}}}^{1}{\ensuremath{\Sigma}}^{+}$ to the ground $X{\phantom{\rule{0.16em}{0ex}}}^{1}{\ensuremath{\Sigma}}^{+}$ state are found to be the only efficient charge-transfer pathway. The spin-orbit coupling does not open other efficient pathways, but alters the potential energy curves and the transition dipole moment for the $A\ensuremath{-}X$ pair of states. The radiative, as well as the nonradiative, charge-transfer cross sections calculated within the ${10}^{\ensuremath{-}3}--10$ cm${}^{\ensuremath{-}1}$ collision energy range exhibit all features of the Langevin ion-atom collision regime, including a rich structure associated with centrifugal barrier tunneling (orbiting) resonances. Theoretical rate coefficients for two Yb isotopes agree well with those measured by immersing Yb${}^{+}$ ions in an ultracold Rb ensemble in a hybrid trap. Possible origins of discrepancy in the product distributions and relations to previously studied similar processes are discussed.

arXiv:1303.3093Physical Review AMay 29, 201335 citations

Charge transfer in cold collisions of rubidium atoms with calcium and ytterbium ions

Svetlana A. Yakovleva, Andrey K. Belyaev, Alexei A. Buchachenko

Low-energy collisions of the Ca and Yb cations with Rb atoms are investigated theoretically using accurate ab initio potential energy curves and coupling matrix elements to elucidate the dominant charge transfer mechanisms. The cross sections calculated at collision energies above 10 −5 cm −1 exhibit the features typical to Langevin ion-atom collision regime, including a rich structure associated with the centrifugal barrier tunnelling (orbiting) resonances. It is shown that the dominant process in Yb + + Rb collisions is the radiative charge transfer, while in the case of Ca + + Rb collisions nonadiabatic transitions due to spin-orbit coupling dominate. Theoretical results are in a good agreement with available experimental data.Low-energy collisions of the Ca and Yb cations with Rb atoms are investigated theoretically using accurate ab initio potential energy curves and coupling matrix elements to elucidate the dominant charge transfer mechanisms. The cross sections calculated at collision energies above 10 −5 cm −1 exhibit the features typical to Langevin ion-atom collision regime, including a rich structure associated with the centrifugal barrier tunnelling (orbiting) resonances. It is shown that the dominant process in Yb + + Rb collisions is the radiative charge transfer, while in the case of Ca + + Rb collisions nonadiabatic transitions due to spin-orbit coupling dominate. Theoretical results are in a good agreement with available experimental data.

Journal of Physics Conference SeriesDec 10, 20141 citation

Charge-transfer cold Yb

{}^{+}

+

Rb collision dynamics is investigated theoretically using high-level ab initio potential energy curves, dipole moment functions, and nonadiabatic coupling matrix elements. Within the scalar-relativistic approximation, the radiative transitions from the entrance $A{\phantom{\rule{0.16em}{0ex}}}^{1}{\ensuremath{\Sigma}}^{+}$ to the ground $X{\phantom{\rule{0.16em}{0ex}}}^{1}{\ensuremath{\Sigma}}^{+}$ state are found to be the only efficient charge-transfer pathway. The spin-orbit coupling does not open other efficient pathways, but alters the potential energy curves and the transition dipole moment for the $A\ensuremath{-}X$ pair of states. The radiative, as well as the nonradiative, charge-transfer cross sections calculated within the ${10}^{\ensuremath{-}3}--10$ cm${}^{\ensuremath{-}1}$ collision energy range exhibit all features of the Langevin ion-atom collision regime, including a rich structure associated with centrifugal barrier tunneling (orbiting) resonances. Theoretical rate coefficients for two Yb isotopes agree well with those measured by immersing Yb

{}^{+}

ions in an ultracold Rb ensemble in a hybrid trap. Possible origins of discrepancy in the product distributions and relations to previously studied similar processes are discussed.