Comparison of hyperfine anomalies in the 5S_{1/2} and 6S_{1/2} levels of ^{85}Rb and ^{87}Rb

TL;DR

This study measures hyperfine splittings in rubidium isotopes, revealing a hyperfine anomaly in the 6S_{1/2} level consistent with previous ground state findings, using two-step spectroscopy.

Contribution

It provides the first measurement of hyperfine anomaly differences in the 6S_{1/2} excited state of rubidium isotopes, confirming the Bohr Weisskopf effect's role.

Findings

Hyperfine anomaly difference of -0.0036(2) in 6S_{1/2} state

Magnetic dipole constants A=239.18(4) MHz for ^{85}Rb and A=807.66(8) MHz for ^{87}Rb

Anomaly consistent with ground state measurements

Abstract

We observe a hyperfine anomaly in the measurement of the hyperfine splitting of the 6S_{1/2} excited level in rubidium. We perform two step spectroscopy using the 5S_{1/2}->5P_{1/2}->6S_{1/2} excitation sequence. We measure the splitting of the 6S1/2 level and obtain for the magnetic dipole constants of ^{85}Rb and ^{87}Rb A = 239.18(4) MHz and A=807.66(8) MHz, respectively. The hyperfine anomaly difference of_{87}delta_{85}=-0.0036(2) comes from the Bohr Weisskopf effect: a correction to the point interaction between the finite nuclear magnetization and the electrons, and agrees with that obtained in the 5S_{1/2} ground state.