High sensitive photoassociation spectroscopy of the Cs molecular and 1g long-range states below the 6S1/2+6P3/2 limit

Highly sensitive photoassociation spectroscopy is reported using the modulation technique in a Cs atom magneto-optical trap. Spectral data are extended to red detunings of 70 cm−1 below the Cs 6S1/2 + 6P3/2 dissociation limit. Long vibrational progressions are assigned to the 0u+ and 1g long-range molecular excited states. Some low-lying vibrational levels are first observed for the 0u+ and 1g states. By fitting the experimental data using the semiclassical LeRoy–Bernstein equation, the long-range molecular coefficients C3 of the 0u+ and 1g states are obtained. The present C3 values are closest to the theoretical values compared with the experimental results reported in earlier publications. Empirical potential curves in the long-range region are derived from these data.