Formation of ultracold X 1Σ+(v''=0) NaCs molecules via coupled photoassociation channels

We report production of ultracold X 1Σ+(v''=0) NaCs molecules via photoassociation. We utilize a combination of spectroscopic techniques to determine formation pathways and label ground-state samples. Efficient free-bound excitation occurs due to coupling between B 1Π and neighboring electronic states in the Na 3S+Cs 6P complex. An f-wave shape resonance contributes to formation of a rotationally pure sample of X 1Σ+(v''=0,J''=1) molecules.