Lifetime determination of the 5d2 3F2 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 5d23F2 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 5d23F2 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)μs. This is in good agreement with the theoretically calculated lifetime of 190μs [V. A. Dzuba and V. V. Flambaum, J. Phys. B 40, 227 (2007)JPAPEH0953-407510.1088/0953-4075/40/1/021]. 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.