A somewhat unexpected hypothesis of the Fermi distribution of photon fluctuations connected with a two-level system is chosen to explain the exponential shape of the absorption line profile in its far wing. A preference is given to studies of the properties of direct interaction between radiation and a matter being in chaotic thermal motion, rather than to the influence of intermolecular interaction on the line shape. A simple exponential form for the far wings of absorption lines is obtained. Examples of modeling absorption in wide spectral regions from 442 to 9648 cm-1 are given for both pure CO2 and CO2-Y mixtures, where Y is one of the buffer gases: N2, H2, He, Ar, or Xe.