6533b7dbfe1ef96bd126fe5b

RESEARCH PRODUCT

New Nuclear Magnetic Moment of Bi209 : Resolving the Bismuth Hyperfine Puzzle

subject

description

A recent measurement of the hyperfine splitting in the ground state of Li-like ${^{208}\mathrm{Bi}}^{80+}$ has established a ``hyperfine puzzle''---the experimental result exhibits a $7\ensuremath{\sigma}$ deviation from the theoretical prediction [J. Ullmann et al., Nat. Commun. 8, 15484 (2017); J. P. Karr, Nat. Phys. 13, 533 (2017)]. We provide evidence that the discrepancy is caused by an inaccurate value of the tabulated nuclear magnetic moment (${\ensuremath{\mu}}_{I}$) of $^{209}\mathrm{Bi}$. We perform relativistic density functional theory and relativistic coupled cluster calculations of the shielding constant that should be used to extract the value of ${\ensuremath{\mu}}_{I}(^{209}\mathrm{Bi})$ and combine it with nuclear magnetic resonance measurements of $\mathrm{Bi}({\mathrm{NO}}_{3}{)}_{3}$ in nitric acid solutions and of the hexafluoridobismuthate(V) ${\mathrm{BiF}}_{6}^{\ensuremath{-}}$ ion in acetonitrile. The result clearly reveals that ${\ensuremath{\mu}}_{I}(^{209}\mathrm{Bi})$ is much smaller than the tabulated value used previously. Applying the new magnetic moment shifts the theoretical prediction into agreement with experiment and resolves the hyperfine puzzle.