Thallium 7p lifetimes derived from experimental data and ab initio calculations of scalar polarizabilities

TL;DR

This paper combines experimental data and ab initio calculations to accurately determine thallium 7p state lifetimes and polarizabilities, providing benchmarks for theoretical methods and future experimental validation.

Contribution

It presents two consistent theoretical calculations of thallium polarizabilities and derives new, highly-accurate 7p state lifetimes from Stark shift measurements.

Findings

Theoretical polarizability predictions agree within 1-2%.

Dominant contribution to polarizability difference comes from state mixing.

New precise 7p lifetime values are extracted from experimental data.

Abstract

Two different theoretical methods have been used to complete a new calculation of polarizability in the thallium 6p_{1/2}, 7s, and 7p_{1/2} states. The predictions of the two methods agree to within 1% for the 6p_{1/2} and 7s states and 2% for 7p_{1/2} state. We find that the theoretical expression for the 6p_{1/2} - 7s transition polarizability difference is dominated (greater than 90% contribution) by mixing of the 7s state with the 7p_{1/2} and 7p_{3/2} states. By comparing the theoretical expression to an existing Stark shift measurement [Doret et al., Phys. Rev. A 66, 052504 (2002)], new, highly-accurate values for the thallium 7p excited-state lifetimes have been extracted. The scalar polarizability of the 7p_{1/2} state is also computed, anticipating an experimental determination of this quantity, which will then enable a high-precision determination of the 6d_{j}-7p_{j^{\prime}} transition rates and provide a benchmark test of the two theoretical approaches in the near future.