Atomic-motion-induced spectroscopic effects that are nonlinear in atomic density in a gas

The interatomic dipole–dipole interaction is commonly thought to be the main physical reason for spectroscopic effects, which are nonlinear in atomic density. However, we have found that free motion of atoms can lead other effects density n , using a previously unknown self-consistent solution Maxwell–Bloch equations mean-field approximation gas two-level with an optical transition at unperturbed frequency ω 0 . These distort Doppler lineshape (shift, asymmetry, broadening), but not associated atom–atom interaction. In particular, case k − 3 &lt;<!-- < <mml:mn>1 (where = / c ) and significant broadening (with respect collisional atomic-motion-induced significantly exceed well-known influence (e.g., Lorentz–Lorenz shift) by more than one order magnitude. Moreover, under some conditions, interval appears non-trivial absent due effects. Thus, existing picture medium should substantially revised.