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Production of optically trapped $^{87}$RbCs Feshbach molecules

We report the production of $^{87}$RbCs Feshbach molecules in a crossed-beam dipole trap. A mixture of $^{87}$Rb and $^{133}$Cs is cooled close to quantum degeneracy before an interspecies Feshbach resonance at 197\,G is used to associate up to $\sim5000$ molecules with a temperature of $\sim300$\,nK. The molecules are confined in the dipole trap with a lifetime of 0.21(1)\,s, long enough for future experiments exploring optical transfer to the absolute ground state. We have measured the magnetic moment of the Feshbach molecules in a magnetic bias field range between 181 and 185\,G to demonstrate the ability to control the character of the molecular state. In addition we have performed Feshbach spectroscopy in a field range from 0 to 1200\,G and located three previously unobserved resonances at high magnetic fields.