This research program uses glancing angle Extended X-ray Absorption Fine Structure (EXAFS) x-ray absorption spectroscopy to investigate the structure of multicomponent glasses and how they are changed by dopant diffusion. The structure of two types of glasses will be investigated. In the first type, a "single alkali" glass, only one elemental component participates in ion exchange with the dopant. In the second "mixed alkali" type, two or more components interact with the dopant cation. Dopant diffusion is expected to occur along "percolation channels" throughout the glass; these should be different in character for the two glass types. Further, these channels are expected to close off near the glass surface due to alkali leaching during surface polishing. The results of this study are expected to have a direct impact on integrated optics technology, micro-optics and gradient-index optics, all of which use ion exchange in glass for fabrication of many of their components. The EXAFS measurements will be in collaboration with Professor G. N. Greaves of the Daresbury Laboratory, an international synchrotron facility in Warrington, England.
