Internal conversion from excited electronic states of $^{229}{\mathrm Th}$ ions

TL;DR

This paper theoretically explores how laser-excited electronic states in thorium ions can enable internal conversion of the low-energy nuclear transition in $^{229}$Th, offering a new way to study its isomeric state.

Contribution

It introduces a novel method to investigate the $^{229}$Th nuclear isomeric state via electronic excitation-induced internal conversion.

Findings

Potential to observe internal conversion in Th$^+$ and Th$^{2+}$ ions.

Proposes experimental setup at IGISOL facility.

Highlights the unique low-energy nuclear transition of $^{229}$Th.

Abstract

The process of internal conversion from excited electronic states is investigated theoretically for the case of the vacuum-ultraviolet nuclear transition of $^{229}{\mathrm Th}$. Due to the very low transition energy, the $^{229}{\mathrm Th}$ nucleus offers the unique possibility to open the otherwise forbidden internal conversion nuclear decay channel for thorium ions via optical laser excitation of the electronic shell. We show that this feature can be exploited to investigate the isomeric state properties via observation of internal conversion from excited electronic configurations of ${\mathrm Th}^+$ and ${\mathrm Th}^{2+}$ ions. A possible experimental realization of the proposed scenario at the nuclear laser spectroscopy facility IGISOL in Jyv\"askyl\"a, Finland is discussed.