Investigations of collisions in SF6 by laser spectroscopy

An investigation is made of saturation resonances in the absorption of the SF₆ molecule found on interaction between strong saturating and weak probe radiation waves from two CO₂ lasers, propagating in an absorbing cell either in the same direction or in opposite directions. For the SF₆ pressure range of 20–350 mTorr, the resonance widths increase linearly with pressure and, within the limits of the experimental accuracy, the resonance width for the opposite waves is twice the resonance width for the unidirectional waves but in both cases the resonance profile for weak saturation is Lorentzian. An interpretation of these results using a model of three relaxation constants for a two-level system with highly degenerate levels suggest that the upper and lower vibrational-rotational levels of SF₆ have the same collisional quenching probability and very few phase-shifting collisions occur.