Near-infrared LIF spectroscopy of HfF

Abstract: The molecular ion HfF$^+$ is the chosen species for a JILA experiment to measure the electron electric dipole moment (eEDM). Detailed knowledge of the spectrum of HfF is crucial to prepare HfF$^+$ in a state suitable for performing an eEDM measurement\cite{Leanhardt}. We investigated the near-infrared electronic spectrum of HfF using laser-induced fluorescence (LIF) of a supersonic molecular beam. We discovered eight unreported bands, and assign each of them unambiguously, four to vibrational bands belonging to the transition $[13.8]0.5 \leftarrow X1.5$, and four to vibrational bands belonging to the transition $[14.2]1.5 \leftarrow X1.5$. Additionally, we report an improved measurement of vibrational spacing of the ground state, as well as anharmonicity $\omega_e x_e$.