Lifetime measurement of the6slevel of rubidium

Abstract

We present a lifetime measurement of the $6s$ level of rubidium. We use a time-correlated single-photon counting technique on two different samples of rubidium atoms, a vapor cell with variable rubidium density, and a sample of atoms confined and cooled in a magneto-optical trap. The $5{P}_{1∕2}$ level serves as the resonant intermediate step for the two-step excitation to the $6s$ level. We detect the decay of the $6s$ level through the cascade fluorescence of the $5{P}_{3∕2}$ level at 780 nm. The two samples have different systematic effects, but we obtain consistent results that averaged give a lifetime of $45.57\ifmmode\pm\else\textpm\fi{}0.17\phantom{\rule{0.3em}{0ex}}\mathrm{ns}$.