Metastable level lifetimes from electron-shelving measurements with ion clouds and single ions

Abstract

The lifetime of the 3d 2 D 5/2 -level in singly-ionized calcium has been measured by the electronshelving technique on different samples of rf trapped ions. The metastable state has been directly populated by exciting the dipole-forbidden 4S 1/2 − 3D 5/2 transition. In ion clouds, the natural lifetime of this metastable level has been measured to be (1095±27) ms. For the single-ion case, we determined a lifetime of (1152±20) ms. The 1σ-error bars at the 2%-level have different origins for the two kinds of experiments: data fitting methods for lifetime measurements in an ion cloud and control of experimental parameters for a single ion. De-shelving effects are extensively discussed. The influence of differing approaches for the processing of the single-ion quantum jump data on the lifetime values is shown. Comparison with recent measurements shows excellent agreement when evaluated from a given method.

Observation of single Ca+ ions for trace isotope analysis

“…8. The dark intervals last between 0.2 s to 2 s. They correspond to the recent lifetime measurements of D 5/2 (for example 1.152 ± 0.020 s [28] and 1.168 ± 0.007 s [29]). More precise measurements are required to compare the lifetime with the previous results.…”

“…One method to identify the single ions is the observation of quantum jumps using the electron shelving method [15]. The quantum jumps of ions such as Hg + [27], Ca + [28,29], Sr + [14,30], Ba + [15] and Yb + [31] have been observed. Fig.…”

“…For the Ca + ion, Doppler laser cooling is realized by utilizing the 397 nm and 866 nm transitions. For the quantum jumps two schemes are available: the forbidden transition from S 1/2 to D 5/2 with an ultra narrow linewidth 729 nm laser [28] and the allowed transitions from D 3/2 to D 5/2 via P 3/2 with an 850 nm laser [29]. Signals similar to those of quantum jumps can be observed when a few ions are loaded by photoionization [24] and escape from the trapping region because of collisions with background gas molecules [32,33].…”

Atomic data from the IRON project

“…For the lower levels (4p 2 P o 1/2 and 4p 2 P o 3/2 ) the effect of polarization interaction is ∼20%. Overall, the differences between the results of our best model and experimental values are less than 5%, except for the level Zeippen (1990), 2 Vaeck et al (1992), 3 Guet & Johnson (1991), 4 Ali & Kim (1988), 5 Kreuter et al (2005), 6 Liaw (1995), 7 Knoop et al (2004), 8 Block et al (1999), 9 Arbes et al (1994), 10 Staanum et al (2004), 11 Gudjons et al (1996). 5d 2 D 5/2 .…”

Evaluation of the ultimate performances of a Ca+ single-ion frequency standard

“…The ground state |g of the calcium ion is S 1/2 and the metastable state |m is D 5/2 with a measured lifetime of 1152 ± 23 ms [16] which leads to a natural width for the clock transition of 138 ± 3 mHz. We require that during the excitation of the transition by the clock laser, all other lasers are shut off.…”