Observation of Feshbach Resonances in an Ultracold Gas of $^52\mathrmCr$
We have observed Feshbach resonances in collisions between ultracold 52Cr atoms. This is the first observation of collisional Feshbach resonances in an atomic species with more than one valence electron. The zero nuclear spin of 52Cr and thus the absence of a Fermi-contact interaction leads to regularly spaced resonance sequences. By comparing resonance positions with multichannel scattering calculations we determine the s-wave scattering length of the lowest 2S+1Σg+ potentials to be 112(14) a0, 58(6) a0, and -7(20) a0 for S=6, 4, and 2, respectively, where a0=0.0529 nm.