Stark shift of the A2Pi(1/2) state in 174YbF.
We have measured the Stark shift of the A2Pi(1/2)-X2Sigma+ transition in YbF. We use a molecular beam triple resonance method, with two laser transitions acting as pump and probe, assisted by an rf transition that tags a single hyperfine transition of the X state. After subtracting the known ground state Stark shift, we obtain a value of 70.3(1.5) Hz/(V/cm)2 for the static electric polarizability of the state A2Pi(1/2) (J=1/2),f by fitting our data to a purely quadratic Stark shift in the interval 0-5 kV/cm. A more exact analysis that does not assume a perfectly quadratic Stark effect yields the value mu(e)=2.48(3) D for the electric dipole moment of the A2Pi(1/2)(v=0) state.