Lifetime determination of high excited states of Rb-85 using a sample of cold atoms

A measurement is presented for the radiative lifetime of the 27D state of R b-85. The technique uses a sample of cold atoms held in a magneto-optical t rap, where Rydberg states (such as the 27D) are excited by a pulsed laser u sing a two-photon transition from the ground state. The excitation is follo wed by pulsed field ionization and ion detection. A delay between excitatio n and ionization allows the exponential decay to be determined, from which the lifetime is extracted. tau (27D) = 27.0 +/- 0.8 mus was thus obtained. (C) 2000 Published by Elsevier Science B.V.