Accession Number : AD0634820

Title :   OPTICAL STUDY OF EXCITIONS IN MIXED ALKALI HALIDES: KI-KBR.

Descriptive Note : Doctoral thesis,

Corporate Author : MATERIALS SCIENCE CENTER CORNELL UNIV ITHACA N Y

Personal Author(s) : Kan, Hung Kuen Alan

Report Date : FEB 1966

Pagination or Media Count : 100

Abstract : The absorption and luminescence properties of KI-KBr mixed crystals were studied over a wide range of KI concentrations. In all systems an absorption band was found which was attributed to a localized exciton formed at an I- - site. The position of the band shifts toward the first exciton absorption peak of pure KI with increasing I- concentration. For dilute I--concentrations the width of the band is twice as large as the width of pure KI or the 82 mole% KI sample. It was also found that the low photon energy absorption edge of this band was an exponential function of photon energy (Urbach's rule) in all mixtures. All the KI-KBr mixed crystals showed a strong luminescence at 80K when excited in the exciton absorption band. In all cases two emission bands were observed. The existence of Urbach's rule and occurence of two emission bands in these mixed-halide crystals is compared with the similar behavior of pure alkali halides. (Author)

Descriptors :   (*ALKALI METAL COMPOUNDS, OPTICAL PROPERTIES), (*POTASSIUM COMPOUNDS, OPTICAL PROPERTIES), (*BROMIDES, OPTICAL PROPERTIES), (*IODIDES, ABSORPTION SPECTRA), LUMINESCENCE, HALIDES, CRYSTALS, X RAY DIFFRACTION, PHASE STUDIES, BAND SPECTRA, PHOTONS, EXCITATION

Subject Categories : Crystallography
      Atomic and Molecular Physics and Spectroscopy
      Optics
      Solid State Physics

Distribution Statement : APPROVED FOR PUBLIC RELEASE