Effect of the Quality of Antirelaxation Coating on the Character of Electromagnetically Induced Transparency in Gas Cells

The dependence of the nature of electromagnetically induced transparency (EIT) in gas cells without a buffer gas on the quality of the antirelaxation coating of the walls, i.e., on the probability of relaxation of the internal state of an atom upon collision with this coating, is analyzed. It is found that, in a number of practically important cases, relaxation on the walls has little effect on the contrast of the EIT resonance, and, under certain conditions, even enhances this effect. For a nondegenerate ground state of atoms, the significant difference is analyzed between two schemes for the implementation of EIT in the cases of Stokes and anti-Stokes scattering of probe radiation, as well as between two types of reflection, specular (elastic) and diffuse, when the atom velocity after reflection does not depend on the velocity before the collision but is determined by the wall temperature. Particular attention is paid to the features of the EIT spectra when the nondegeneracy of the excited state of atoms is taken into account.