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 τ = 1064(17) ms improves earlier results and agrees with the value recently computed by Liaw using the Brueckner approximation.
The natural lifetime of the metastable
4d2D5∕2 state in
88Sr+ has been measured using a single laser-cooled, trapped ion. The ion was prepared in the
4d2D5∕2 state by laser excitation of the $5s\phantom{\rule{0.2em}{0ex}}^{2}S_{1∕2}\ensuremath{-}4d\phantom{\rule{0.2em}{0ex}}^{2}D_{5∕2}$ quadrupole transition at 674 nm. The decay time was measured by using Dehmelt's electron shelving method to monitor the ion's electronic state. Two separate investigations were conducted under slightly different experimental conditions. 160 000 decay times from the
4d2D5∕2 state were observed in total, and two different methods for determining the statistical value of the measured lifetime have been compared. Systematic effects have also been estimated, and including these effects yields a value of $\ensuremath{\tau}=390.8(1.6)\phantom{\rule{0.3em}{0ex}}\mathrm{ms}$ ($1\ensuremath{\sigma}$ uncertainty) for the natural lifetime.
We present a measurement of the lifetime of the metastable
3d2D5∕2 state in the
40Ca+ ion, using the so-called shelving technique on a string of five Doppler laser-cooled ions in a linear Paul trap. A detailed account of the data analysis is given, and systematic effects due to unwanted excitation processes and collisions with background gas atoms are discussed and estimated. From a total of 6805 shelving events, we obtain a lifetime $\ensuremath{\tau}=1149\ifmmode\pm\else\textpm\fi{}14(\text{stat}.)\ifmmode\pm\else\textpm\fi{}4(\text{sys}.)\text{ms}$, a result which is in agreement with the most recent measurements.