Photoassociation of cesium atoms into Cs-2 3(3)Pi(g) state at 543.5 nm

We report absorption measurements in pure cesium vapor at high temperatures , when triplet absorption bands in the spectral interval 540-560 nm emerge within the singlet molecular bands which slowly diminish due to efficient t hermal dissociation. The absorption bands have been identified as stemming from extrema in the Cs-2 3 (3)Pi(g)-a (3)Sigma(u)(+) difference potential c urve. We performed a quasiclassical simulation which agrees well with exper imental observation. Since the Cs-2 a 3 Sigma(u)(+) State is only weakly bo und, the observed absorption bands at 543.5 and 557 nm represent free-hound transitions or the photoassociation process.