Radiative lifetime of the1S0metastable state in doubly charged Kr ions

Abstract

The radiative lifetime of the $4{s}^{2}4{p}^{4}{\phantom{\rule{0.16em}{0ex}}}^{1}{S}_{0}$ metastable state in $\mathrm{K}{\mathrm{r}}^{2+}$ ions has been experimentally determined using an electrostatic ion trap of the ion-beam storage type. The radiative lifetime was obtained by measuring the number of 350-nm photons emitted during the ${}^{1}{S}_{0}{\ensuremath{\rightarrow}}^{3}{P}_{1}$ magnetic dipole transition of $\mathrm{K}{\mathrm{r}}^{2+}$ as a function of the storage time. The storage lifetime of the $\mathrm{K}{\mathrm{r}}^{2+}$ beam in the trap, which is a correction term in the determination of the radiative lifetime, was measured by detecting Kr neutrals produced by electron capture collisions with residual gases in the trap. We have obtained a lifetime value of $17.4\ifmmode\pm\else\textpm\fi{}0.4\phantom{\rule{0.16em}{0ex}}\mathrm{ms}$, which is larger than the previous experimental results, but consistent with theoretical predictions.