Precision measurement of the metastable 6s[3/2]2lifetime in xenon

Using a magneto-optical trap to isolate an isotopically pure sample of xenon, we determine the metastable 6s [3/2${]}_2$ state lifetime by measuring the rate of VUV emisson due to magnetic quadrupole decay. We find lifetimes of 42.9(9) s and 42.4(13) s for ${}_{}{}^{132}{}_{}{}^{}\mathrm{Xe}$ and ${}_{}{}^{136}{}_{}{}^{}\mathrm{Xe}$, respectively (1σ uncertainties). These values are less than half the theoretical predictions. We also find that nuclear-spin-induced decay produces a much shorter metastable lifetime in ${}_{}{}^{129}{}_{}{}^{}\mathrm{Xe}$.