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P. Beiersdorfer; A. L. Osterheld; J. H. Scofield; J. R. Crespo López-Urrutia; K. Widmann

doi:10.1103/PhysRevLett.80.3022

Measurement of QED and Hyperfine Splitting in the $2 s_{1 / 2}$ - $2 p_{3 / 2}$ X-Ray Transition in Li-like ${}^{209}B i^{80 +}$

P. Beiersdorfer, A. L. Osterheld, J. H. Scofield, J. R. Crespo López-Urrutia, and K. Widmann

Phys. Rev. Lett. 80, 3022 – Published 6 April 1998

Abstract

A measurement of the ${2 s}_{1 / 2} - {2 p}_{3 / 2}$ x-ray transition in trapped Li-like ${Bi}^{80 +}$ ions was made that resolved the $0.820 \pm 0.026 eV$ hyperfine splitting of the $({1 s}^{2} 2 s)_{F = 4, 5}$ ground configuration, providing the first such measurement in a multielectron highly charged ion. The intensity ratio of the two components is shown to be a new electron density diagnostic. The statistically averaged $2788.139 \pm 0.039 eV$ energy of the ${2 s}_{1 / 2} - {2 p}_{3 / 2}$ transition provides the most accurate test of QED in a high- $Z$ ion to date, demonstrating the need for including higher-order terms in the Lamb shift calculations.