  We will show that isotropic collisions of electrons and protons with neutral
hydrogen can lead to creation of net orientation of the atomic levels in the
presence of a magnetic field. Consequently, the emitted Stokes-V profile of the
spectral lines can be almost symmetric in contrast to the typical antisymmetric
signature of the Zeeman effect. Moreover, the amplitude of the symmetric lobe
can be significantly higher than the amplitude of the antisymmetric components.
This mechanism is caused by a $\pm{M}$ symmetry breaking of the collisional
transitions between different Zeeman sublevels. We will show an example of our
first results for the H$\alpha$ line. This new mechanism could perhaps explain
the net circular polarization of spectral lines observed in some solar limb
observations and which are currently not understood. However, our results are
very preliminary and more developments are needed for going further on.
