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Bose-Einstein condensation of 85Rb by direct evaporation in an optical dipole trap

We report a simple method for the creation of Bose-Einstein condensates of $^{85}$Rb by direct evaporation in a crossed optical dipole trap. The independent control of the trap frequencies and magnetic bias field afforded by the trapping scheme permits full control of the trapped atomic sample, enabling the collision parameters to be easily manipulated to achieve efficient evaporation in the vicinity of the 155 G Feshbach resonance. We produce nearly pure condensates of up to $4\times10^4$ atoms and demonstrate the tunable nature of the atomic interactions.