TY - JOUR

T1 - Unexpectedly large difference of the electron density at the nucleus in the 4p2P1/2,3/2 fine-structure doublet of Ca +

AU - Shi, Chunyan

AU - Gebert, Florian

AU - Gorges, Christian

AU - Kaufmann, Simon

AU - Nörtershäuser, Wilfried

AU - Sahoo, Bijaya Kumar

AU - Surzhykov, A.

AU - Yerokhin, Vladimir A.

AU - Berengut, Julian C.

AU - Wolf, Fabian

AU - Heip, J. C.

AU - Schmidt, Piet Oliver

N1 - Funding information: We acknowledge financial support from the German Federal Ministry for Education and Research (BMBF) under contract 05P15RDFN1, the Helmholtz International Center for FAIR (HIC for FAIR) within the LOEWE program by the State of Hesse, the State of Lower Saxony, Hannover, Germany and DFG through grants SCHM2678/3-1 and CRC 1227 DQ-mat, project B05. SK received support from HGS-Hire. BKS acknowledges use of the Vikram-100 HPC cluster at the Physical Research Laboratory, Ahmedabad for performing calculations. V.A.Y acknowledges support by the Russian Federation program for organizing and carrying out scientific investigations. WN thanks G.W.F. Drake, Z.C. Yan, and R. Neugart for stimulating discussions. PS and WN thank K. Pachucki for stimulating discussions.

PY - 2016/12/6

Y1 - 2016/12/6

N2 - We measured the isotope shift in the 2S 1 / 2→ 2P 3 / 2 (D2) transition in singly ionized calcium ions using photon recoil spectroscopy. The high accuracy of the technique enables us to compare the difference between the isotope shifts of this transition to the previously measured isotopic shifts of the 2S 1 / 2→ 2P 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.

AB - We measured the isotope shift in the 2S 1 / 2→ 2P 3 / 2 (D2) transition in singly ionized calcium ions using photon recoil spectroscopy. The high accuracy of the technique enables us to compare the difference between the isotope shifts of this transition to the previously measured isotopic shifts of the 2S 1 / 2→ 2P 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.

UR - http://www.scopus.com/inward/record.url?scp=85003632873&partnerID=8YFLogxK

U2 - 10.1007/s00340-016-6572-z

DO - 10.1007/s00340-016-6572-z

M3 - Article

AN - SCOPUS:85003632873

VL - 123

JO - Applied Physics B: Lasers and Optics

JF - Applied Physics B: Lasers and Optics

SN - 0946-2171

IS - 1

M1 - 2

ER -