Influence of the neighboring transition on polarization gradient cooling

g =4→F_e ^′=5 transition. As the detuning becomes larger, the equilibrium temperature becomes lower. When the detuning is larger than 150 MHz, the influence of the F_g=4→F_e ^′=4 transition also becomes significant. We show our numerical analysis of polarization gradient cooling, taking into account actual sublevels of the ground state and two excited states. We conclude that it is preferable to use a detuning of greater than 180 MHz, to get both a high deceleration and low equilibrium temperature. Received: 25 September 1996/Revised version: 10 January 1997