Optical Saturation of a Single Vibration–Rotation Transition in the ν3 Fundamental of SF6

A well-resolved vibration–rotation transition in the ν3 infrared fundamental of SF6 has been revealed at 200°K by using the tuned laser spectroscopy technique. The frequency-dependent saturation behavior of that transition has been studied at low pressures, and the results fitted to theoretically predicted curves. From the pressure dependence of the saturation parameter, the quantity (γ′ / γ)Aab, which is the product of the Einstein Aab coefficient and the ratio of the dephasing collision rate and the rotational relaxation rate, was determined to be 53 sec−1. This is considered as a good upper bound for the Einstein Aab coefficient itself.