Excitation of the isomeric ^{229m}Th nuclear state via an electronic bridge process in ^{229}Th^+

TL;DR

This paper proposes a method to excite the isomeric state of thorium-229 using an electronic bridge process in Th^+ ions, enabling precise determination of the nuclear transition frequency with feasible laser excitation rates.

Contribution

It introduces a novel electronic bridge scheme for nuclear excitation in Th^+ ions, combining advanced electronic structure calculations to estimate excitation rates.

Findings

Estimated nuclear excitation rate of 10 s^{-1} with conventional lasers.

High-accuracy determination of the nuclear transition frequency.

Electronic structure calculations support the feasibility of the scheme.

Abstract

We consider the excitation of the nuclear transition ^{229g}Th - ^{229m}Th near 7.6 eV in singly ionized thorium via an electronic bridge process. The process relies on the excitation of the electron shell by two laser photons whose sum frequency is equal to the nuclear transition frequency. This scheme allows to determine the nuclear transition frequency with high accuracy. Based on calculations of the electronic level structure of Th^+ which combine the configuration-interaction method and many-body perturbation theory, we estimate that a nuclear excitation rate in the range of 10 s^{-1} can be obtained using conventional laser sources.