The temperature of optical molasses for two different atomic angular momenta

We have measured the temperature of laser-cooled Rb atoms in optical molasses as a function of laser intensity and detuning. For both⁸⁵Rb and⁸⁷Rb, cooled on the F = 3 F' = 4and F = 2 F’ = 3 transitions, respectively, the temperatures are proportional to the ratio oflaser power and detuning for a wide range of these parameters. We observe a small butsignificant difference between the two isotopes. We also show the results of three-dimensionalsemi-classical numerical calculations. Our results favor a model which includes atomic localizationin optical standing waves.