Photoassociation of ultracold NaCs via (4)
Ω=1 yields deeply-bound, highly polar X
1Σ+ states
We demonstrate that a photoassociation resonance detuned less than a wave number below the Cs
62P3/2 atomic line can be used to create a deeply bound molecular sample of ultracold polar NaCs. We assign $1 {}^{1}{\ensuremath{\Sigma}}^{+}$ (
v=4,5,6,11,19) vibrational levels utilizing a pulsed depletion spectroscopic method (scanning
700 cm${}^{\ensuremath{-}1}$ at a time) in which we observe the $1 {}^{1}{\ensuremath{\Sigma}}^{+}\ensuremath{\rightarrow}2 {}^{1}{\ensuremath{\Sigma}}^{+}\ensuremath{-}1 {}^{3}\ensuremath{\Pi}$ 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.
We present photoassociation spectroscopy of ultracold NaCs molecules formed in a dual-species magneto-optical trap. Excited-state molecules are formed in states correlating to the Na(3S 1/2 )+Cs(6P 3/2 ) asymptote. We assign the most prominent observed vibrational progression to the Ω=2 long range state based on a comparison with ab initio potentials. Molecules are secondarily excited before decaying to deeply bound levels of the electronic ground X 1 Σ + state where they are ionized and detected by time-of-flight mass spectroscopy.