Accession Number : AD0664943

Title :   IMPURITY EFFECTS ON THE IONIZATION STATES OF F-AGGREGATE COLOR CENTERS IN SODIUM FLUORIDE.

Descriptive Note : Doctoral thesis,

Corporate Author : CORNELL UNIV ITHACA N Y MATERIALS SCIENCE CENTER

Personal Author(s) : Chandra,Ashoka

Report Date : JAN 1968

Pagination or Media Count : 218

Abstract : The role of hydroxide and peroxide impurities on color-center properties in sodium fluoride were studied with several crystals grown with the Kyropoulous technique. The optical absorption in peroxide doped samples consists primarily of three bands at 275 millimicrons, 235 millimicrons and 195 millimicrons respectively. The production of F centers is determined almost entirely by impurities with a small contribution due to intrinsic processes. The large coloration in hydroxide and peroxide doped samples are explained on the basis of photochemical reactions involving impurities which act as sources of anion vacancies and electrons. Important differences were observed in hydroxide and peroxide doped samples in relation to the charge state of the aggregate centers. Electron-deficient centers are stabilized and the probability of their formation is enhanced in hydroxide doped samples. In peroxide doped samples the excess electron centers are favored. Several new absorption bands were observed in hydroxide and peroxide doped samples.

Descriptors :   (*SODIUM COMPOUNDS, *COLOR CENTERS), (*FLUORIDES, *CRYSTAL DEFECTS), IMPURITIES, IONS, HYDROXIDES, PEROXIDES, ABSORPTION SPECTRA, BAND SPECTRA, X RAYS, DAMAGE, RADIATION EFFECTS, PHOTOCHEMICAL REACTIONS, ELECTRON PARAMAGNETIC RESONANCE, LUMINESCENCE, THESES

Subject Categories : Solid State Physics

Distribution Statement : APPROVED FOR PUBLIC RELEASE