An Electron Electric Dipole Moment Search in the $^3\Delta_1$ Ground State of Tungsten Carbide Molecules

We report on progress towards constructing and characterizing a continuous tungsten carbide (WC) molecular beam for an electron electric dipole moment (EDM) search\footnote{J.\ Lee et al., Atomic Physics \textbf{XXI}, 190 (2008).}. Tungsten atoms are evaporated from a resistively heated filament and tungsten carbide molecules are formed through a reaction with methane: $\textrm{W}+\textrm{CH}_4 \rightarrow \textrm{WC} + 2\textrm{H}_2$. WC has a $^3\Delta_1$ ground state with its two valance electrons in a $\sigma\delta$ molecular orbital configuration\footnote{K.\ Balasubramanian, J.\ Chem.Phys.\textbf{112}, 7425 (2000).}$^,$\footnote{S.\ M.\ Sickafoose et al., J.\ Chem.\ Phys.\ \textbf{116}, 993 (2002).}$^,$\footnote{D.\ Rothgeb et al., J.\ Chem.Phys.\textbf{129}, 114304 (2008).}. This molecular structure has several unique advantages for an electron EDM search and arises in other diatomic species such as HfF$^+$\footnote{\texttt{http://jilawww.colorado.edu/bec/CornellGroup/}.}$^,$\footnote{E.R.Meyer et al., Phys.\ Rev.\ A \textbf{73}, 062108 (2006).}, ThF$^+$$^{5,}$\footnote{E.\ R.\ Meyer et al., Phys.\ Rev.\ A \textbf{78}, 010502 (2008).}, and ThO$^{7,}$\footnote{A.\ C.Vutha et al., Atomic Physics \textbf{XXI}, 191 (2008).}.