Lifetimes of the9sand8plevels of atomic francium

Abstract

We use time-correlated single-photon counting techniques on a sample of $^{210}\mathrm{Fr}$ atoms confined and cooled in a magneto-optical trap to measure the lifetimes of the $9{S}_{1∕2},\phantom{\rule{0.3em}{0ex}}8{P}_{3∕2}$, and $8{P}_{1∕2}$ excited levels. We populate the $9{S}_{1∕2}$ level by two-photon resonant excitation through the $7{P}_{1∕2}$ level. The direct measurement of the $9{S}_{1∕2}$ decay through the $7{P}_{3∕2}$ level at 851 nm gives a lifetime of $107.53\ifmmode\pm\else\textpm\fi{}0.90\phantom{\rule{0.3em}{0ex}}\mathrm{ns}$. We observe the decay of the $9{S}_{1∕2}$ level through the $8{P}_{3∕2}$ level at 423 nm and the $8{P}_{1∕2}$ level at 433 nm down to the $7{S}_{1∕2}$ ground level, and indirectly determine the lifetimes of these to be $83.5\ifmmode\pm\else\textpm\fi{}1.5\phantom{\rule{0.3em}{0ex}}\mathrm{ns}$ and $149.3\ifmmode\pm\else\textpm\fi{}3.5\phantom{\rule{0.3em}{0ex}}\mathrm{ns}$, respectively.