Theoretical isotope shifts in neutral barium

TL;DR

This paper presents a theoretical analysis of isotope shifts in neutral barium, deriving nuclear charge radius changes from experimental data and comparing theoretical predictions with experimental measurements.

Contribution

It provides ab initio electronic factors for key barium transitions and investigates their consistency with experimental isotope shift data.

Findings

Consistent nuclear charge radius changes from two spectral lines.

Discrepancy between theoretical isotope shifts and laser spectroscopy measurements for certain transitions.

Abstract

The present work deals with a set of problems in isotope shifts of neutral barium spectral lines. Some well known transitions ($6s^2~^1S_0-6s6p~^{1,3}P^o_1$ and $6s^2~^1S_0-6p^2~^3P_0$) are first investigated. Values of the changes in the nuclear mean-square charge radius are deduced from the available experimental isotope shifts using our ab initio electronic factors. The three sets $\{ \delta\langle r^2\rangle^{A,A'}\} $ obtained from these lines are consistent with each other. The combination of the available nuclear mean-square radii with our electronic factors for the $6s5d~^3D_{1,2} -6s6p~^{1}P^o_1$ transitions produces isotope shift values in conflict with the laser spectroscopy measurements of Dammalapati et al. (Eur. Phys. J. D 53, 1 (2009)).