Optical Absorption and Luminescence of Excitons in Silver Halides Containing Isoelectronic Impurities. Part I. AgBr:I-

Abstract

Various correlations are observed between absorption and luminescence spectra of silver halides with isoelectronic impurities at low temperature. In Part I, the bound exciton transitions are described mainly on AgBr:I - together with related cases of AgCl:Br - and AgCl:I - . In AgBr:I - , mirror-image like relations are observed between absorption and emission spectra with zero phonon line at the center. Multiphonon structures are observed in both spectra and the energy of coupled phonon is substantially smaller in absorption that in emission. The difference in phonon energies reflects strong binding of excitons with phonons discussed by Toyozawa and Hermanson. In absorption spectra, additional structures are observed and interpreted as creating excitons in higher excited states. In emission, one phonon sidebands are observed reflecting phonon spectrum in pure AgBr. Discussions are also made on temperature variation of absorption spectrum and on asymmetric intensity distribution between absorption and emi...