Rotational Collision Numbers of N2, O2, CO, and CO2 from Thermal Transpiration Measurements

Abstract

Thermal transpiration results which were determined at an (assumed) characteristic temperature of 504°K are reported for all of the noble gases and for N₂, O₂, CO, and CO₂. The helium data are found to be anomalous when viewed in terms of the dusty‐gas model for thermal transpiration. Application of the model in the zeroth differential approximation yields the following rotational collision numbers for the polyatomic molecules: N₂, 6.0; O₂, 2.2; CO, 1.3; CO₂, 1.9.