Sodium Bose-Einstein condensates in the F=2 state in a large-volume optical trap -: art. no. 090401

We have investigated the properties of Bose-Einstein condensates of sodium atoms in the upper hyperfine ground state. Condensates in the high-field seeking \F=2,m(F)=-2> state were created in a large volume optical trap from initially prepared \F=1,m(F)=-1> condensates using a microwave transition at 1.77 GHz. We found condensates in the stretched state \F=2,m(F)=-2> to be stable for several seconds at densities in the range of 10(14) atoms/cm(3). In addition, we studied the clock transition \F=1,m(F)=0>-->\F=2,m(F)=0> in a sodium Bose-Einstein condensate and determined a density-dependent frequency shift of (2.44+/-0.25+/-0.5)x10(-12) Hz cm(3).