Radiative decay of excited ${}^1{P}_1$ states to metastables is expected to limit attainable lifetimes in magneto-optic traps (MOTs) containing alkaline-earth-metal-like atoms. We present measurements of power-dependent loss from a ${(6s}^2{)}^1{S}_0{-\left(6s6p\right)\mathrm{}}^1{P}_1$ ytterbium MOT, show that the observed power dependence is consistent with radiative decay from the ${\mathrm{}\left(6s6p\right)\mathrm{}}^1{P}_1$ excited state leading to population of lower-lying metastable states, and determine the ${\mathrm{}\left(6s6p\right)\mathrm{}}^1{P}_1$-to-metastable state decay rate. With weak excitation of the ${(6s}^2{)}^1{S}_0{-\left(6s6p\right)\mathrm{}}^1{P}_1$ trapping transition, MOT lifetimes approaching 800 ms are observed.

• Received 4 November 1999

DOI:https://doi.org/10.1103/PhysRevA.61.051401