REMPI spectroscopy of HfF

The spectrum of electronic states at 30000–33000cm−1 in hafnium fluoride has been studied using (1+1) resonance-enhanced multi-photon ionization (REMPI) and (1+1′) REMPI. Six Ω′=3/2 and ten Π1/2 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 Π1/2 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 Π1/2 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+.