Modification of D₂-line absorption contours of alkali atoms in antirelaxation coated cells

Absorption features in cells with antirelaxation coating in D₂ -lines of alkali metal atoms due to the competition of cyclic and open transitions lying within the Doppler contour are studied. In cells of this type ensemble of atoms is optically pumped over all velocities and the entire volume of the cell during the characteristic time T, which noticeably exceeds local pumping times related to resonant atomic velocities. If the frequency scanning T, the retardation effect results in significant distortion of the laser wave absorption contour and to emergence of the hysteresis phenomenon. The developed theory for a realistic scheme of atomic levels with one cyclic and two open transitions describes experimentally observed absorption contours, their dependence on the light power and the frequency scanning direction. (paper)