Dissociation of ultracold cesium Rydberg-ground molecules

We report the experimental measurements of the decay rate of polar cesium nD5/2 - 6S1/2 Rydberg-ground molecules with a large principal quantum number range of 35 ≤ n ≤ 40. Rydberg molecules are prepared employing the method of two-photon photoassociation and the molecular (atomic) ions, due to autoionization (blackbody photoionization), are detected with a microchannel plate detector. The decay rate Γ of the vibrational ground state of the deep and shadow bound molecules for triplet (TΣ) and mixed singlet-triplet (S,TΣ) are measured by fitting the molecular population with the exponential function. Comparing with the parent atom, the decay rate of the polar Rydberg-ground molecule shows an obvious increase with a magnitude of a few μs. The possible dissociation mechanism of polar Rydberg-ground molecules including a collisional decay, blackbody induced decay, and coupling of adjacent Rydberg states and tunneling decay are discussed in detail. The theoretical model is induced to simulate the measurements, showing agreement.