Precision determination of the ground-state hyperfine separation inHg+199using the ion-storage technique

Abstract
By an optical double-resonance experiment on Hg+199, suspended in a rf quadrupole trap, we determined the ground-state hyperfine separation. Linewidths as small as 4 Hz have been observed. The final result of Δνhfs=40507347997.8±1.0 Hz includes corrections to zero magnetic field and zero kinetic energy. The accuracy of the result and possible improvements lead to the feasibility of a new frequency standard in the microwave region.