An excellent candidate molecule for the measurement of the electron's electric dipole moment (eEDM) is thorium monofluoride (${\mathrm{ThF}}^{+}$) because the eEDM–sensitive state, ${}^3{\mathrm{\Delta }}_1$, is the electronic ground state, and thus is immune to decoherence from spontaneous decay. We perform spectroscopy on $X{}^3{\mathrm{\Delta }}_1$ to extract three spectroscopic constants crucial to the eEDM experiment: the hyperfine coupling constant, the molecular frame electric dipole moment, and the magnetic $g$ factor. To understand the impact of thermal blackbody radiation on the vibrational ground state, we study the lifetime of the first excited vibrational manifold of $X{}^3{\mathrm{\Delta }}_1$. We perform ab initio calculations, compare them to our results, and discuss prospects for using ${\mathrm{ThF}}^{+}$ in an eEDM experiment at JILA.

• Received 29 November 2021
• Accepted 3 February 2022

DOI:https://doi.org/10.1103/PhysRevA.105.022823