Wave function of the "prepared" state of the active (absorbing the light) molecule, appeared after collision accompanied by the absorption of quantum at a frequency, far from resonance, is obtained. This wave function does not coincide with any of its eigenstates. The corresponding nonequilibrium density matrix is constructed. The dependence of the density matrix of the center of mass subsystem on fluctuations of the center of mass coordinates and impulses is shown.
longwave approximation, light absorption, spectralline wings, nonLTE, nonequilibrium density matrix