Radiation damage in inorganic solids - spectroscopic investigations of structure and mechanism.
thesisposted on 19.11.2015, 08:44 by R. S. Eachus
PART I A number of interesting inorganic radicals have been prepared by exposing polycrystalline materials doped with suitable anions to high energy radiation. The species (NaH)+, BO32-, NO32-, C1032-, and C1042- are discussed in detail in Chapters III, IV and V. The data derived from their ESR and electronic spectra are used both as an aid in identification and as a probe of their electronic and molecular structures. PART II The magnetic and optical properties of six paramagnetic species (C103, C1032-, C102, (C1-Cl02)-, Cl2- and 0-3), produced by the ?-irradiation of KCl03, are discussed in detail in Chapter VI. Their configurations in the chlorate lattice are deduced, and a tentative mechanism for radiation damage in KC103 is formulated. There is substantial evidence for the existence of the free radical Cl00 from kinetic studies in the gas phase. Chapter III describes how this species was isolated in KC104 and frozen 90% H2SO4 matrices from the UV-photolysis of trapped Cl02 radicals. In these environments the 'peroxy-chlorine' species slowly isomerizes back to C102 and a mechanism for this interconversion process is suggested. PART III Trapped silver atoms are known to be formed when glasses containing argentous ions are exposed to high energy radiation. In Chapter VIIIA we outline the identification of several inequivalent silver-containing centres, including trapped silver atoms, AgH+ cations and aquated silver atoms, in frozen aqueous H2SO4 and show how the natures of the radiolysis products were dependent upon the acid concentration of the matrix. Furthermore, the species (AgOR)+ have been detected in irradiated alcoholic solutions containing Ag+ ions. The thermally initiated decomposition of these silver radicals has been followed by ESR and optical spectroscopy in Chapters VIIIB. In both acid and alcoholic environments, radical annihilation must proceed via aggregation and the polynuclear species Ag2+, (Ag2H)2+ and Ag4n+ have been identified as intermediates in this process. Wherever possible the cadmium analogues of the silver radicals have been prepared to facilitate a comparison of their magnetic properties and structures.