FINE AND HYPERFINE STRUCTURE OF 173YbF

$^{174}$YbF has been used for some time in attempts to determine the electrostatic T,P violating electron electric dipole moment (eEDM). It was recently pointed out [1] that $^{173}$YbF may be an avenue for determining an EDM induced by the magnetic quadrupole moment (MQM). As in the eEDM case, here the molecular properties of $^{173}$YbF are experimentally advantageous. We report a detailed analysis of the fine and hyperfine structure in the X$^{2}$$\Sigma$$^{+}$ state from a combined analysis of rotational and optical transitions. Numerous hyperfine components in the N=4 $\rightarrow$ 5 and N=3 $\rightarrow$ 4 rotational transitions were recorded using a separated field pump/probe microwave optical double residence technique. Fourier transform microwave spectroscopy was used to record five features of the N=0 $\rightarrow$ 1 rotational transition. This rotational data was combined with precisely measured (0,0) A$^{2}$$\pi$$_{1/2}$ - X$^{2}$$\Sigma$$^{+}$ optical transitions of a cold molecular beam sample. Resulting fine and hyperfine parameters will be discussed and compared with recent theory [2]. The research at Arizona State University was supported by a grant from the Heising Simons Foundation (Grant 2018-0681). 1. V.V. Flambaum, et al., arXiv:1810.02477v2 [hep-ph] (10 Dec 2018) 2. P. Schwerdtfeger, et al., Mol. Phys. 114, 1110 (2016