Spectroscopic Effects Nonlinear in Atomic Density Caused by the Free Motion of Atoms in a Gas

SummaryWe have found new effects nonlinear in the atomic density caused by the free motion of atoms, considering the self-consistent solution of the Maxwell-Bloch equations in the mean-field approximation and for one-atomic density matrix in a gas of two-level atoms. These effects distort the Doppler lineshape (shift, asymmetry, broadening), but are not associated with an atom-atom interaction. In particular, in the case of dominating Doppler broadening of the linewidth (in respect with collisional broadening), founded atomic-motion-induced effects significantly exceed the well-known influence of the dipole-dipole interatomic interaction (e.g., Lorentz-Lorenz shift) by more than one order of magnitude.