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 4s2S1/2 − 4p2P1/2 and 4p2P1/2 − 3d2D3/2 transitions. The strong fluorescence of these lines disappears when we excite the ions simultaneously by a third laser on the 3d2D3/2 − 4p2P3/2 line because of population trapping in the metastable 3d2D5/2 state, into which the 4p2P3/2 level decays. From the time dependence of the fluorescence after blocking the third laser we determined the lifetime of the 3d2D5/2 level. Our result of τ = 1064(17) ms improves earlier results and agrees with the value recently computed by Liaw using the Brueckner approximation.

Spatial separation of atomic states in a laser-cooled ion crystal

A laser cooled ion crystal containing several hundred Ca+ ions has been stored in a linear Paul trap. Cooling is provided by a red detund laser at the 4S1/2−4P1/2 resonance transition. A second laser serves for repumping of those ions which decay from the excited 4P1/2 level to the metastable 3D3/2 state. The ions can be additionally excited by a third laser to a long lived metastable 3D5/2 energy level which decouples them from the cooling laser radiation. The light pressure acting upon the laser cooled ions pushes them into the direction of the laser beam. The ions in the metastable 3D5/2 state, however, do not experience any light pressure force and diffuse to the crystal side which poin…

3d

We have measured the lifetime of the metastable 3D 5/2 level in Ca+ using the “quantum jump" technique on a single stored and laser cooled ion in a linear Paul trap. We found a linear dependence of the measured decay rate on the power of the laser which repumps the ions from the long lived 3D 3/2 level. This can be explained by off-resonant depletion of the 3D 5/2 level. The proper lifetime of this level is obtained by a linear extrapolation of the measured lifetime to zero laser power. We obtain 1100(18) ms in agreement with theoretical calculations. The observed systematic change of the decay rate resolves discrepancies between earlier experiments in which this effect had not been conside…

Shifts of the 3D - 4P transitions in different isotopes of positive calcium ions

A sample of stable isotopes containing the masses 40, 42, 43 and 44 was stored under buffer-gas conditions in a Paul ion trap. After population of the metastable 3D levels by spontaneous decay of the laser-excited 4P state we observed laser-induced fluorescence when we scanned a laser across the different 3D - 4P fine-structure lines at 850, 854 and 866 nm. From the Doppler-limited lines of these transitions we deduced the isotope shifts, which are of the order of several GHz due to the large specific mass shift of the metastable 3D levels.

Spatial separation of atomic states in a laser cooled ion crystal

A laser cooled ion crystal containing several hundred Ca+ ions has been stored in a linear Paul trap. Cooling is provided by a red detund laser at the 4S1/2−4P1/2 resonance transition. A second laser serves for repumping of those ions which decay from the excited 4P1/2 level to the metastable 3D3/2 state. The ions can be additionally excited by a third laser to a long lived metastable 3D5/2 energy level which decouples them from the cooling laser radiation. The light pressure acting upon the laser cooled ions pushes them into the direction of the laser beam. The ions in the metastable 3D5/2 state, however, do not experience any light pressure force and diffuse to the crystal side which poin…

Influence of anharmonicities of a Paul trap potential on the motion of stored ions