COLLISIONAL BEATS OF POLARIZATIONS OF LIGHT IN A MAGNETIC-FIELD UPON LASER EXCITATION

A theoretical analysis is performed of the anisotropic collisional rel axation of polarization moments of atoms excited by a monochromatic la ser light in a uniform magnetic field perpendicular to the laser beam. Equations are derived that determine the dependence of rate constants of collisional relaxation on the shift of the laser frequency from th e center of a Doppler profile of a spectral line, on the masses of col liding particles, the temperature, and density of a gas medium. The ma gnetic field is shown to induce the beats of alignment of atomic angul ar momenta, which is inclined by 45 degrees to the laser beam. These b eats, in turn, due to the anisotropic collisional interconversion of a lignment and orientation, cause the beats of orientation of angular mo menta and accompanying beats of the circular polarization of light, ob served along the direction of the magnetic field. The anisotropy of th e relative velocity distribution of emitting atoms and atoms of a surr ounding gas medium is an important condition for the appearance of a s ignal of the beats of circular polarization.