Excitons in rare-gas crystals

Abstract

The paper is a survey of experimental and theoretical results on exciton states in crystals of xenon, krypton, argon and neon. The absorption and luminescence spectra of the crystals and the band structure of electron and exciton states are analysed. Some features of the exciton-phonon interaction in pure and doped crystals are discussed. In contrast with other types of molecular crystal, those of rare gases can simultaneously support free and localized excitons. All features of the exciton spectra, in particular the hydrogen-like series of light absorption, the rich pattern of luminescence and the absorption and emission bands due to impurity centres, have been given a natural explanation in terms of the intermediate-radius exciton strongly bonded to the crystal lattice. These investigations of excitons in atomic cryocrystals have revealed a number of new effects and extended our knowledge of the cooperative excitation states of dielectrics.