ESTIMATION OF CROSS-SECTIONS FOR ENERGY-TRANSFER IN BIMOLECULAR COLLISIONS

The proper definition of a cross section for energy transfer in bimole cular collisions is considered. Three models transforming smooth impac t parameter dependence into hit or miss cross section form are discuss ed. The property dependence of the concept of a collision cross sectio n is investigated. Translational energy cross sections (viscosity, dif fusion, deflection energy) are found to be smaller than internal energ y cross sections (thermal conductivity, thermal activation). An effect ive potential analysis of the concept of cross section shows that both radial and rotational collisions must be considered. Properly defined theoretical (effective potential, MD simulation) and experimental cro ss sections for Br2-Br2 show satisfactory agreement.