Precise lifetime determination of the metastable 3d(2)D(5/2) level in Ca+ by ''electron shelving''

Ca+ ions confined as a cloud in a Paul trap were excited and cooled by radiation from two lasers, tuned to the 4s(2)S(1/2)-4p(2)P(1/2) and 4p(2)P(1/2)-3d(2)D(3/2) transitions. The strong fluorescence of these lines disappears when we excite the ions simultaneously by a third laser on the 3d(2)D(3/2)-4p(2)P(3/2) line because of population trapping in the metastable 3d(2)D(5/2) state, into which the 4p(2)P(3/2) level decays. From the time dependence of the fluorescence after blocking the third laser we determined the lifetime of the 3d(2)D(5/2) level. Our result of tau = 1064(17) ms improves earlier results and agrees with the value recently computed by Liaw using the Brueckner approximation.