Precise transition amplitude and polarizability measurements in ²⁰⁸Pb

Recently, we completed a measurement of the forbidden (6s²6p²) ³P₀ - ³P₂ electric quadrupole (E2) transition amplitude in Pb as a new test of ab initio atomic theory work in this Group IV atom[1]. There, we compared the E2 absorptivity to the precisely-calculable (and comparably-weak) M1 transition absorptivity. We have now begun to study several excited-state E1 transitions in lead (at 368 and 406 nm). By choosing E1 transitions which originate in states whose thermal populations in our heated quartz cells are in 10^-4 to 10^-6 range, the observed absorptivity of these E1 transitions is comparable to the ‘forbidden’ ground-state transitions noted above. Through precise measurement of Faraday optical rotation amplitudes at carefully-monitored interaction region temperatures, we can convert relative absorptivity measurements into absolute E1 linestrength values. Preliminary results for two excited-state E1 transition amplitudes will be presented. We also present our continuing progress towards high-precision polarizability measurements in Pb using Faraday Rotation spectroscopy from an atomic beam apparatus, which we hope will serve as a new test of atomic wavefunction models in this heavy, multivalence atomic system.



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