Low-Temperature viscosity cross sections measured in a supersonic argon beam II

Previously, values of the thermal-conductivity (viscosity) cross section for argon deduced from velocity distributions measured near the center line of a free jet deviated unexpectedly from the temperature dependence predicted for low temperatures. Subsequently, the molecular-beam sampling system and data reduction procedures used in that previous study were upgraded and the measurements were repeated. Cross-section values were obtained at temperatures more than an order of magnitude below the normal condensation temperature of argon. The temperature dependence of the deduced effective hard-sphere diameter is in good agreement with the predicted dependence, but the magnitudes are about 10 percent less than the predicted values