Lifetime determination of the 5d(2) F-3(2) state in barium using trapped atoms

Magneto-optically trapped atoms enable the determination of lifetimes of metastable states and higher lying excited states like the 5d(2) F-3(2) state in barium. The state is efficiently populated by driving strong transitions from metastable states within the cooling cycle of the barium magneto-optical trap (MOT). The lifetime is inferred from the increase of MOT fluorescence after the transfer of up to 30% of the trapped atoms to this state. The radiative decay of the 5d(2) F-3(2) state cascades to the cooling cycle of the MOT with a probability of 96.0(7)% corresponding to a trap loss of 4.0(7)% and its lifetime is determined to 160(10) mu s. This is in good agreement with the theoretically calculated lifetime of 190 mu s [V.A. Dzuba and V.V. Flambaum, J. Phys. B 40, 227 (2007)]. The determined loss of 4.0(7)% from the cooling cycle is compared with the theoretically calculated branching ratios. This measurement extends the efficacy of trapped atoms to measure lifetimes of higher, long-lived states and validate the atomic structure calculations of heavy multielectron systems.