Quantum spin state selectivity and magnetic tuning of ultracold chemical reactions of triplet alkali-metal dimers with alkali-metal atoms

Abstract

We use coupled-channel statistical calculations to explore the effects of external magnetic fields and hyperfine interactions on the ultracold chemical reactions of triplet alkali-metal dimers with alkali-metal atoms. Using the Na + NaLi(a 3 Σ + ) → Na2( 1 Σ + g ) + Li reaction as a representative example, we find that the reaction rates are sensitive to the initial hyperfine states of the reactants, and that the chemical reaction of fully spin-polarized NaLi(a 3 Σ + , v = 0, N = 0) molecules with Na atoms is suppressed by a factor of 10-100 compared to that of unpolarized reactants. We interpret these findings within the adiabatic state model, which treats the chemical reaction as a sequence of nonadiabatic transitions between the initial high-spin (non-reactive) and final low-spin (reactive) diabatic states of the reaction complex. Our results demonstrate that it is possible to efficiently control the chemical reactions of open-shell alkali-metal dimers with alkali-metal atoms by tuning the internal hyperfine states of the reactants and by applying an external magnetic field.

Control of reactive collisions by quantum interference

“…We avoid the need for absolute sodium density measurements by comparing the measured decay rate to the decay rate of the mixture in a non-stretched spin state colliding on a reactive doublet potential. This decay is reliably predicted to occur with the s-wave universal rate constant which is well known for our system [32].…”

“…Since the calibration measurements have systematic uncertainties, we include a fifth fitting parameter, in form of an overall normalization factor, N . We use an accurate theoretical value of ā calculated for triplet ground-state NaLi+Na, ā = 56.1a 0 with 1.5% uncertainty [32]. Fig.…”

Interaction potentials, electric moments, polarizabilities, and chemical reactions of YbCu, YbAg, and YbAu molecules

“…Unfortunately, the spin-relaxation mediated by the magnetic spin-spin and second-order spin-orbit coupling may lead to reactive singlet intermolecular interaction potentials [67,68]. Except for the atom-exchange reactions, the trimer formation reactions may be another path of chemical losses [33,65,66]:…”