EXCITONS IN SIO2 - A REVIEW

In this paper, excitonic properties of crystalline and glassy SiO2 are reviewed. Experimental spectroscopic data (optical absorption and reflection spectra, as well as spectra of luminescence and its excitation), luminescence decay kinetics at different temperatures, and photoelectric properties - photoconductivity and photoelectron emission - were used to deterMine excitons in SiO2. Information on migration of excitons was obtained on the basis of energy transport to impurity luminescence centers, the latter being detectors of quasiparticles. Determination of excitonic properties in glassy SiO2 was based on the comparison of the observed phenomena in crystalline and glassy materials in approximately the same conditions. Structural peculiarities are analyzed comparing optical phenomena in crystalline alpha-quartz and cristobalite and in fused silica of four types. Models of excitons are based on propositions of chemical bond theory and total energy adiabatic potential.