Approximative treatments of rotational relaxation

Calculations following a stochastic treatment and a sudden approximation both in their semiclassical versions are presented. The collisions problem considered is in both cases the relaxation of molecular nitrogen in an argon gas. The results are compared with exact dynamical results from earlier investigations. The comparisons are presented in some modified surprisal plots, where the surprisals are plotted as gaussians in the angular momentum j, i.e. against (j - j0)2, where j0 is the initial value of j. (Auth.)