Lifetime of the metastable 6s′ [1/2]_0 clock state in xenon

To investigate the potential of a proposed optical frequency standard, we have measured the lifetime of the metastable 6s' [(1/2)](0) state in xenon. Magneto-optically trapped xenon atoms were prepared in the 6s' [(1/2)](0) state, and the time dependence of the vacuum-ultraviolet decay signature was analyzed. The total decay rate of 75(3) s(-1) is the sum of a 7.8(38)-s(-1) spontaneous emission rate (1-sigma uncertainties) and a much larger deexcitation rate that is due to a transition driven by room-temperature blackbody radiation.