Ramsey fringes in a thermal beam of Yb atoms

We use the Ramsey separated oscillatory fields (SOF) technique in a ${400}^{\circ }$C thermal beam of Yb atoms to measure the Larmor precession frequency with high precision. For the experiment, we use the strongly-allowed ${}^1{S}_0\to {}^1{P}_1$ transition at $399$ nm, and choose the odd isotope ${}^{171}$Yb with nuclear spin $I=1\mathrm{/}2$, so that the ground state has only two magnetic sublevels $m_F=\pm 1\mathrm{/}2$. With a magnetic field of $22.2$ G and a separation of about $400$ mm between the oscillatory fields, the central Ramsey fringe is at $16.64$ kHz and has a width of $350$ Hz. The technique can be readily adapted to a cold atomic beam, and should be useful in experiments searching for a permanent electric dipole moment (EDM) in atoms.