The isotope shift (IS) in two visible lines of neutral lead involving transitions 6s2 6p7s 1P1-6s2 6p21S0 (λ5OO.6 nm) and 6s2 6p8s 3P1-6s2 6p21S0 (λ520.3nm) have been measured using a Fabry-Perot interferometer. The isotope shifts between even isotopic pairs were found to be: v208-v206=73.3±0.9 mK and v208-v204=121.4±1.1 mK for 6p7s configuration and v208-v206=70.1±0.6 mK and v208-v204=135.7±0.8 mK for 6p8s configuration. The displacements of the centers of gravity of isotope 207 with respect to isotope 208 were determined to be v208-v207 CG=46.4±1.2 mK and v208-v207 CG=44.9±1.1 mK for 6p7s and 6p8s configurations, respectively.
T. J. Wasowicz,
"Isotope shift study in two visible lines: 500.6 nm and 520.3 nm of Pb I", Proc. SPIE 5849, Fifth Workshop on Atomic and Molecular Physics, (1 June 2005); doi: 10.1117/12.629486; https://doi.org/10.1117/12.629486