Field broadening and shifts of nonlinear power resonances in low-pressure gases

A calculation is made of the absorption coefficient of a standing-wave field in a gas of two-level molecules allowing for transit effects to within the second order of the saturation parameter. The rate of the field broadening of a nonlinear power resonance is investigated for various dimensions of a light beam. An analysis is also made of the rates of the field shift of the maximum of such a nonlinear resonance because of the quadratic Doppler effect and hyperfine structure of the line.