Effective collision cross sections for the viscomagnetic effect in a pure gas of linear molecules

Using Liouville-space algebra, general expressions are derived for the three effective collision cross sections governing the viscomagnetic effect in a pure gas of linear molecules. These cross sections are presented in terms of S-matrix elements in the total-J representation since it is especially useful for the dynamical approximation procedures that have recently come into vogue. The results obtained here are briefly compared with those for diatom–atom systems and, where possible, with similar results previously obtained via other methods.