Knowledge Bank

The identification of HfF$\mathrm{<mrow\; data-mjx-texclass="ORD">+</mrow>}$ as a possible candidate for a $\backslash textit\{d\}\_\{e\}\}$ measurement has stimulated new interest in the spectroscopy of both HfF$\mathrm{<mrow\; data-mjx-texclass="ORD">+</mrow>}$ , \textbf{134}, 201102 (2011).}$\mathrm{<mrow\; data-mjx-texclass="ORD">,</mrow>}$ , \textbf{546}, 1 (2012).}$\mathrm{<mrow\; data-mjx-texclass="ORD">,</mrow>}$ , \textbf{272}, 32 (2012).} and neutral HfF ,\textbf{276-277}, 49 (2012).}. Studies of the neutral are relevant because photoionization schemes can be used to produce the cations. More importantly, computational methodologies used to predict the electronic wavefunction of HfF$\mathrm{<mrow\; data-mjx-texclass="ORD">+</mrow>}$ can be effectively assessed by making a comparison of predicted and experimental properties of the neutral, which are more readily determinable. The (1,0)[17.9]2.5 -$X2\Delta 3/2$ band of hafnium monofluoride (HfF) has been recorded using high-resolution laser-induced fluorescence spectroscopy both field-free and in the presence of a static electric field. The field-free spectra of $\mathrm{<mrow\; data-mjx-texclass="ORD">177</mrow>}$HfF, $\mathrm{<mrow\; data-mjx-texclass="ORD">179</mrow>}$HfF, and $\mathrm{<mrow\; data-mjx-texclass="ORD">180</mrow>}$HfF were model to generate a set of fine and hyperfine parameters for the $X2\Delta 3/2$ (v=0) and [17.9]2.5 (v=1) states. The observed optical Stark shifts for the $\mathrm{<mrow\; data-mjx-texclass="ORD">180</mrow>}$HfF isotopologue were analyzed to produce the molecular frame electric dipole moments of 1.66(1)D and 0.419(7)D for the $X2\Delta 3/2$ and [17.9]2.5 states, respectively. A two-step $ab\; initio$ calculation consisting of a two-component generalized relativistic effective core potential calculation (GRECP) followed by a restoration of the proper four-component wavefunction was performed to predict the properties of ground state HfF.