The Burstein-Moss effect, the shift of the edge of the region of intrinsic absorption of light by a semiconductor towards higher frequencies as the concentration of conduction electrons increases and they fill the conduction band. Thus, in a crystal of InSb with intrinsic conduction the absorption edge corresponds (at T=300 K) to the wavelength λcr=7.2 µm; after the sample has been doped with donors to a concentration of 5·1018cm-3, λcr=3.2 µm. The Burstein-Moss effect is a consequence of the Pauli principle: optical quantum transitions are possible only on condition that the state into which the electron passes is not occupied by another electron. It was established independently of each other by the American physicist E. Burstein and the English physicist T. S. Moss in 1954.