Isotope shifts and hyperfine structure measurements in low-lying transitions of atomic lead

We recently completed the first ever direct measurement of the 939 nm (6s²6p²) ³P₀ - ³P₂ electric quadrupole (E2) transition in Pb, using Faraday rotation spectroscopy. We found our measured E2 amplitude to be in excellent agreement with the theoretical value predicted from a new ab initio calculation at the 1% level of accuracy [1]. Continuing our exploration of this transition, we have recently completed a measurement of the 939 nm E2 transition isotope shift (TIS) among several stable isotopes of lead as well as the ²⁰⁷Pb hyperfine constant for the ³P₂ excited state. A value for these isotope shifts can be inferred by combining several published measurements of TIS values for other low-lying transitions, and we have found our direct measurement to be in significant disagreement with these inferred values. Using several complementary methods for laser frequency scan calibration and linearization, we have expanded our scope to measure TIS and hyperfine structure in multiple low-lying transitions in lead using both direct absorption and Faraday rotation spectroscopy, and employing several different IR, blue, and near-UV diode laser systems. Comparisons to previous measurements and latest results will be presented.



[1] – Maser et al., Phys. Rev. A 100, 052506 (2019)