REMPI Spectroscopy of HfF

TL;DR

This study uses REMPI spectroscopy to characterize electronic states of hafnium fluoride, providing molecular constants and insights into autoionization spectra relevant for quantum state control in eEDM experiments.

Contribution

It reports new molecular constants for HfF electronic states and demonstrates state-specific autoionization spectra, aiding quantum control for eEDM measurements.

Findings

Characterized six $ m{ ilde{A}}$ $ m{ ilde{X}}$ vibronic bands.

Observed distinct autoionization spectra for different intermediate states.

Estimated electronic energies of excited states using isotope shifts.

Abstract

The spectrum of electronic states at 30000--33000 cm$^{-1}$ in hafnium fluoride has been studied using (1+1) resonance-enhanced multi-photon ionization (REMPI) and (1+1$'$) REMPI. Six $\Omega' = 3/2$ and ten $\Pi_{1/2}$ vibronic bands have been characterized. We report the molecular constants for these bands and estimate the electronic energies of the excited states using a correction derived from the observed isotope shifts. When either of two closely spaced $\Pi_{1/2}$ electronic states is used as an intermediate state to access autoionizing Rydberg levels, qualitatively distinct autoionization spectra are observed. The intermediate state-specificity of the autoionization spectra bodes well for the possibility of using a selected $\Pi_{1/2}$ state as an intermediate state to create ionic HfF$^+$ in various selected quantum states, an important requirement for our electron electric dipole moment (eEDM) search in HfF$^+$.