Effect of the photodeposition of tin on the consolidation of porous Vycor glass

UV photolysis of (CH)3SnI adsorbed onto porous Vycor glass yields changes in refractive index similar to those obtained with other organometallic precursors, but subsequent annealing of the samples fails to encapsulate the structure within a consolidated glass. The glass remains porous and structures extending 2–4 μm above the surface of the glass appear in the exposed regions. UV photolysis of adsorbed (CH)3SnI yields (CH)3Sn–OHSi which is oxidized to SnO and SnO2 during the subsequent annealing. Sn(IV) displaces boron from the glass matrix, which diffuses to the surface of the glass, where it reacts with moisture to form crystalline H3BO3 extending above the surface of the glass. Loss of boron from the regions exposed to UV light changes the viscosity of the glass and its rate of consolidation thereby creating porous regions within an otherwise consolidated glass. These regions extend 6–8 μm into the glass, and adsorption of luminescent dyes suggests these porous regions possess a microenvironment essentially equivalent to that of the original porous glass.