High-Precision Faraday Polarimetry Measurements of Lead Transition Amplitudes and Static Polarizabilities

We recently completed a direct measurement of the very weak (6s²6p²) ³P₀→³P₂ 939 nm electric quadrupole (E2) transition in atomic lead using an optical polarimeter with microradian resolution.¹ A Faraday rotation spectroscopy technique was used to compare the transition strengths of the E2 transition to the (6s²6p²) ³P₀→³P₁ 1279 nm (M1) transition in a lead vapor cell heated to between 800 and 950 ̊C. We found excellent agreement with new ab initio theoretical calculations of relevance to parity nonconservation in lead.  Using this highly-sensitive technique, we are now studying optical rotation signals in both an atomic beam apparatus, where we will measure the (6s²6p²) ³P₁→(6s²6p7s) ³P₀ 368 nm (E1) transition using transverse (Doppler-narrowed) Faraday spectroscopy, and in a newly constructed heat pipe oven, whose enhanced sensitivity compared with the vapor cell will provide a boost to the 939 nm signal strength of more than an order of magnitude. We are now undertaking atomic-beam polarizability measurements of excited states of lead, as well as attempting a first direct measurement of the extremely weak (6s²6p²) ³P₀→¹D₂ 466 nm (E2) transition in the heat pipe oven, both of which will serve as new, sensitive tests of atomic theory. Current experimental results will be presented.

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