Abstract
We establish the general expression of the (de)polarizing rates for the case of an arbitrary symmetry of the anisotropic collisions. From this general formula, we recover the limiting case of the depolarization rates by isotropic collisions. We show the theoretical possibility of an alignment-to-orientation conversion mechanism by anisotropic collisions, leading to circular impact polarization emergence independently of the magnetic field strengths. We investigate the role of isotropic collisions with neutral hydrogen in the formation of the polarized Ba II lambda 4554 line and, thus, in the determination of the magnetic field. On the other hand, we present our new results obtained for the depolarization rates of the levels of the CH molecule using different coupling schemes to treat the dynamics of collisions. These results allow us to study the variation of the depolarization rates as a function of rotational J-levels, and to confirm our previous results concerned with the SiO molecule.