PRODUCTION AND RELAXATION CROSS-SECTIONS FOR THE SHEAR VISCOSITY SENFTLEBEN-BEENAKKER EFFECT .1. FORMAL EXPRESSIONS AND THEIR COUPLED-STATES AND INFINITE-ORDER-SUDDEN APPROXIMATIONS FOR ATOM-DIATOM SYSTEMS

Starting from kinetic theory collision integrals obtained from a generalized Boltzmann equation for a linear molecule in a bath of atomic perturbas and using Liouville (vector) space algebra, general expressions are derived for the three cross sections determining the shear viscosity Senftleben-Beenakker effects. These expressions are presented in terms of S-matrix elements in the total-J representation since this representation is especially useful for dynamical calculation and approximation procedures. Coupled-states and infinite-order-sudden dynamical approximations are then introduced and expressions obtained for the three cross sections in initial-l, final-l, and average-l labeling schemes. All cross sections simplify greatly when initial or final-l labeling is employed but little or not at all when average-l labeling is used. Nonetheless, even when the latter choice is made, less work will be involved than would be required for the corresponding full close-coupled or coupled-states calculation. © 1979 American Institute of Physics.