Near-dissociation photoassociative production of deeply bound NaCs molecules

We demonstrate that a photoassociation resonance detuned less than a wave number below the Cs 6 2P_3/2 atomic line can be used to create a deeply bound molecular sample of ultracold polar NaCs. We assign 1 1Σ⊃+ (v=4,5,6,11,19) vibrational levels utilizing a pulsed depletion spectroscopic method (scanning ~700 cm⊃-1 at a time) in which we observe the 1 1Σ⊃+→2 1Σ⊃+-1 3Π vibrational progression. These data are compared with results from a hot-molecule collision-enhanced laser-induced fluorescence experiment and shown to be in good agreement. This technique is a powerful tool to experimentally determine the population distribution in any ultracold molecular system.