D1 and D2 lines in $^{6,7}$Li including QED effects

TL;DR

This paper provides highly accurate theoretical calculations of lithium isotope transition energies including QED effects, compares them with experimental data, and uses the results to determine nuclear charge radius differences.

Contribution

It presents new QED-corrected predictions for lithium D-line transitions and resolves discrepancies in Bethe logarithm calculations, supporting nuclear property determinations.

Findings

QED-corrected transition energies agree with experiments

Disagreement found in Bethe logarithm calculations with recent literature

Nuclear charge radius difference between isotopes confirmed

Abstract

Accurate theoretical predictions including leading QED corrections for $2^2P_{1/2} - 2^2S_{1/2}$ (D1) and $2^2P_{3/2} - 2^2S_{1/2}$ (D2) transition energies have been obtained for $^{6,7}$Li isotopes. Our results for the Bethe logarithms $\ln k_0(2^2S) = 5.178\,169(4)$, and for mass polarization corrections $\Delta \ln k_0(2^2S) = 0.113\,81(3)$ are in disagreement with ones obtained recently in the literature. In contrast, results $\ln k_0(2^2P) = 5.179\,81(7)$ and $\Delta \ln k_0(2^2P) = 0.111\,3(5)$ are in good agreement with them. From our theoretical predictions and recent measurements of $^{6,7}$Li D-lines at NIST, we determine the mean square charge radius difference between $^7$Li and $^6$Li nuclei, in agreement with determinations based on the $3^2S_{1/2}-2^2S_{1/2}$ transition, what demonstrates consistency of atomic spectroscopy determination of fundamental properties of nuclei.