Unexpectedly large difference of the electron density at the nucleus in the 4p ${}^2$P${}_{1/2,3/2}$ fine-structure doublet of Ca${}^{+}$

Abstract

We measured the isotope shift in the ${}^2$S${}_{1/2}$-${}^2$P${}_{3/2}$ (D2) transition in singly-ionized calcium ions using photon recoil spectroscopy. The high accuracy of the technique enables us to resolve the difference between the isotope shifts of this transition to the previously measured isotopic shifts of the ${}^2$S${}_{1/2}$-${}^2$P${}_{1/2}$ (D1) line. This so-called splitting isotope shift is extracted and exhibits a clear signature of field shift contributions. From the data we were able to extract the small difference of the field shift coefficient and mass shifts between the two transitions with high accuracy. This J-dependence is of relativistic origin and can be used to benchmark atomic structure calculations. As a first step, we use several ab initio atomic structure calculation methods to provide more accurate values for the field shift constants and their ratio. Remarkably, the high-accuracy value for the ratio of the field shift constants extracted from the experimental data is larger than all available theoretical predictions.

10 pages, 6 figures, 7 tables

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Cited by in corpus (4)

• Improved isotope-shift-based bounds on bosons beyond the Standard Model through measurements of the ${}^2$D${}_{3/2}{-}^2$D${}_{5/2}$ interval in Ca${}^{+}$
• Sensitivity to New Physics of Isotope Shift Studies using the Coronal Lines of Highly Charged Calcium Ions
• Non-linear isotope-shift effects in Be-like, B-like, and C-like argon
• QED theory of the specific mass shift in atoms