More on Vibrational Relaxation in SO2/Ar Mixtures

A new system for making sound velocity and absorption measurements in gases has been constructed using capacitance transducers, resulting in a system having greater accuracy than that previously employed. Using this system and an improved method for correcting for the tube effect, the relaxation absorption has been measured in a mixture of 25% SO2/75% Ar to an accuracy sufficient to distinguish between the series and parallel relaxation schemes in SO2. The measurements favor the series process with energy passing through the bending mode into the stretching modes by vibration—vibration (v—v) energy transfer. The effectiveness of SO2/Ar collisions in producing v—v exchanges is of the order of 0.05 that of SO2/SO2 collisions.