DOPPLER-FREE DARK RESONANCES FOR HYPERFINE MEASUREMENTS AND ISOTOPE SHIFTS IN CA+ ISOTOPES IN A PAUL TRAP

We have observed ''dark resonances'' in the Lambda-type level structure, formed by the 4S(1/2) ground state, the 4P(1/2) excited state and the low lying metastable 3D(3/2) state in the Calcium ion, confined in a Paul radio-frequency trap. These Doppler-free and potentially very narrow resonances were used to determine the magnetic dipole hyperfine interaction constant A for the 4P(1/2) and 3D(3/2) State of Ca-43(+), giving -142(8)MHz and -48.3(1.6)MHz, respectively. From measurements of the P-D (El) and S-D (E2) transition wavelength in a mixture of Ca-43(+) and Ca-40(+) we determined the isotope shifts of these lines.