New experiments were proposed recently to investigate the regime of cold atomic and molecular ion-atom collision processes in a special hybrid neutral-atom--ion trap under high-vacuum conditions. We study the collisional cooling of laser precooled ${\mathrm{Ca}}^{+}$ ions by ultracold Na atoms. Modeling this process requires knowledge of the radiative lifetime of the excited singlet $A{}^{1}{\ensuremath{\Sigma}}^{+}$ state of the $(\mathrm{NaCa}{)}^{+}$ molecular system. We calculate the rate coefficient for radiative charge transfer using a semiclassical approach. The dipole radial matrix elements between the ground and the excited states, and the potential curves were calculated using complete active space self-consistent field and M\"oller-Plesset second-order perturbation theory with an extended Gaussian basis, 6-311+G $(3df).$ The semiclassical charge-transfer rate coefficient was averaged over a thermal Maxwellian distribution. In addition, we also present elastic collision cross sections and the spin-exchange cross section. The rate coefficient for charge transfer was found to be $2.3\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}16}{\mathrm{cm}}^{3}/\mathrm{sec},$ while those for the elastic and spin-exchange cross sections were found to be several orders of magnitude higher $(1.1\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}8}{\mathrm{cm}}^{3}/\mathrm{sec}$ and $2.3\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}9}{\mathrm{cm}}^{3}/\mathrm{sec},$ respectively). This confirms our assumption that the milli-Kelvin regime of collisional cooling of calcium ions by sodium atoms is favorable with the respect to low loss of calcium ions due to the charge transfer.New experiments were proposed recently to investigate the regime of cold atomic and molecular ion-atom collision processes in a special hybrid neutral-atom--ion trap under high-vacuum conditions. We study the collisional cooling of laser precooled ${\mathrm{Ca}}^{+}$ ions by ultracold Na atoms. Modeling this process requires knowledge of the radiative lifetime of the excited singlet $A{}^{1}{\ensuremath{\Sigma}}^{+}$ state of the $(\mathrm{NaCa}{)}^{+}$ molecular system. We calculate the rate coefficient for radiative charge transfer using a semiclassical approach. The dipole radial matrix elements between the ground and the excited states, and the potential curves were calculated using complete active space self-consistent field and M\"oller-Plesset second-order perturbation theory with an extended Gaussian basis, 6-311+G $(3df).$ The semiclassical charge-transfer rate coefficient was averaged over a thermal Maxwellian distribution. In addition, we also present elastic collision cross sections and the spin-exchange cross section. The rate coefficient for charge transfer was found to be $2.3\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}16}{\mathrm{cm}}^{3}/\mathrm{sec},$ while those for the elastic and spin-exchange cross sections were found to be several orders of magnitude higher $(1.1\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}8}{\mathrm{cm}}^{3}/\mathrm{sec}$ and $2.3\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}9}{\mathrm{cm}}^{3}/\mathrm{sec},$ respectively). This confirms our assumption that the milli-Kelvin regime of collisional cooling of calcium ions by sodium atoms is favorable with the respect to low loss of calcium ions due to the charge transfer.

arXiv:physics/0209077Physical Review AApr 11, 200392 citations

Excitation Transfer in Atomic Collisions

Boris Michailovich Smirnov

Journal of Experimental and Theoretical PhysicsFeb 1, 19670 citations

Resonant Transfer and Excitation in Ion-Atom Collisions

Ramakrishnan Chelakara Parameswaran

Jan 1, 19920 citations

Angular Momentum Transfer at the Chemo-ionization and Spin Exchange Processes. Interaction between Spin Polarized Metastable Helium Atoms

Victor A. Kartoshkin

In the collision of spin-polarized atoms, the transmission of electron polarization between colliding particles is possible. A similar situation occurs in a collision, for example, between alkali atoms in the ground state. If one of the colliding particles is in an excited state and its energy is sufficient for ionization of the collision partner, then along with the elastic process (spin exchange), an inelastic process (ionization) is also possible, as a result of these processes polarization can also be transferred to the partner. Simultaneously occurring elastic and inelastic processes at the collision between two helium atoms are possible if these atoms are in the metastable (23S1) state. The paper discusses the interaction between spin-polarized metastable atoms of helium-3 and helium-4 isotopes under conditions of optical pumping of atoms. Complex interaction potentials of the atoms under consideration were constructed and on their basis, the spin exchange and chemo-ionization cross-sections were calculated. Using these cross-sections, expressions for the transfer of orientation and alignment from one atom to another were obtained.In the collision of spin-polarized atoms, the transmission of electron polarization between colliding particles is possible. A similar situation occurs in a collision, for example, between alkali atoms in the ground state. If one of the colliding particles is in an excited state and its energy is sufficient for ionization of the collision partner, then along with the elastic process (spin exchange), an inelastic process (ionization) is also possible, as a result of these processes polarization can also be transferred to the partner. Simultaneously occurring elastic and inelastic processes at the collision between two helium atoms are possible if these atoms are in the metastable (23S1) state. The paper discusses the interaction between spin-polarized metastable atoms of helium-3 and helium-4 isotopes under conditions of optical pumping of atoms. Complex interaction potentials of the atoms under consideration were constructed and on their basis, the spin exchange and chemo-ionization cross-sections were calculated. Using these cross-sections, expressions for the transfer of orientation and alignment from one atom to another were obtained.

Mediterranean Journal of ChemistryOct 7, 20220 citations

Ionization by the Collision of Pairs of Metastable Atoms

Manfred A. Biondi

Physical ReviewMay 1, 195151 citations

{\mathrm{Ca}}^{+}

ions by ultracold Na atoms. Modeling this process requires knowledge of the radiative lifetime of the excited singlet $A{}^{1}{\ensuremath{\Sigma}}^{+}$ state of the

(\mathrm{NaCa}{)}^{+}

molecular system. We calculate the rate coefficient for radiative charge transfer using a semiclassical approach. The dipole radial matrix elements between the ground and the excited states, and the potential curves were calculated using complete active space self-consistent field and M\"oller-Plesset second-order perturbation theory with an extended Gaussian basis, 6-311+G

(3df).

The semiclassical charge-transfer rate coefficient was averaged over a thermal Maxwellian distribution. In addition, we also present elastic collision cross sections and the spin-exchange cross section. The rate coefficient for charge transfer was found to be $2.3\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}16}{\mathrm{cm}}^{3}/\mathrm{sec},$ while those for the elastic and spin-exchange cross sections were found to be several orders of magnitude higher $(1.1\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}8}{\mathrm{cm}}^{3}/\mathrm{sec}$ and $2.3\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}9}{\mathrm{cm}}^{3}/\mathrm{sec},$ respectively). This confirms our assumption that the milli-Kelvin regime of collisional cooling of calcium ions by sodium atoms is favorable with the respect to low loss of calcium ions due to the charge transfer.