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

Abstract

We demonstrate that it is possible to efficiently control ultracold chemical reactions of alkali-metal atoms colliding with open-shell alkali-metal dimers in their metastable triplet states by choosing the internal hyperfine and rovibrational states of the reactants as well as by inducing magnetic Feshbach resonances with an external magnetic field. We base these conclusions on coupled-channel statistical calculations that include the effects of hyperfine contact and magnetic-field-induced Zeeman interactions on ultracold chemical reactions of hyperfine-resolved ground-state Na and the triplet NaLi(a${}^3{\Sigma }^{+}$) producing singlet Na${}_2$(${}^1{\Sigma }_g^{+}$) and a Li atom. We find that the reaction rates are sensitive to the initial hyperfine states of the reactants. The chemical reaction of fully spin-polarized, high-spin states of rotationless NaLi(a${}^3{\Sigma }^{+},v=0,N=0$) molecules with fully spin-polarized Na 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 reaction as a sequence of nonadiabatic transitions between the initial non-reactive high-spin state and the final low-spin states of the reaction complex. In addition, we show that magnetic Feshbach resonances can similarly change reaction rate coefficients by several orders of magnitude. Some of these resonances are due to resonant trimer bound states dissociating to the $N=2$ rotational state of NaLi(a${}^3{\Sigma }^{+},v=0$) and would thus exist in systems without hyperfine interactions.

6 pages, 3 figures

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Cited by in corpus (11)

• Control of reactive collisions by quantum interference
• A Feshbach resonance in collisions between ultracold ground state molecules
• Spectrum of Feshbach resonances in NaLi $+$ Na collisions
• Spin-conservation propensity rule for three-body recombination of ultracold Rb atoms
• Preparation of a quantum degenerate mixture of ${}^{23}$Na${}^{40}$K molecules and ${}^{40}$K atoms
• Signatures of Non-universal Quantum Dynamics of Ultracold Chemical Reactions of Polar Alkali-dimer Molecules with Alkali-metal Atoms: Li(${}^2$S) +NaLi($a^3{\Sigma }^{+}$) $\to$ Na(${}^2$S) + Li${}_2$($a^3{\Sigma }_u^{+}$)
• Magnetic Feshbach resonances in ultracold atom-molecule collisions
• Nuclear spin relaxation in cold atom-molecule collisions
• Spin hierarchy in van der Waals molecule formation via ultracold three-body recombination
• Total angular momentum representation for state-to-state quantum scattering of cold molecules in a magnetic field
• Ultracold molecular collisions in magnetic fields: Efficient incorporation of hyperfine structure in the total rotational angular momentum representation