  The frequency correlation properties of the radiation from an atom in a
strong field in resonance with neighboring transitions are considered. It is
shown that the difference in frequency correlation in two-photon and stepwise
processes decreases with increase of the external field. The spectral
compositions of the Doppler-broadened resonance scattering and fluorescence are
analyzed. It is shown that in these cases the Doppler line width is
anisotropic.
