Cathodoluminescence and depth profiles of tin in float glass

Cathodoluminescence (CL) spectra have been recorded from float glass samples and the data used to determine the depth profile of tin introduced from the float process. The luminescence data were interpreted in terms of intrinsic emission bands at 380 and 410 nm and well resolved extrinsic emission bands resulting from the tin impurities at 575 and 630 nm. The presence of the tin produces an optical waveguide in the glass surface as a result of the float production process. It was therefore possible to depth profile the tin by measurement of the waveguide modes. Overall, the depth of tin diffusion was up to 8-9 mu m in the samples studied. The lifetimes and intensity of the signals are temperature dependent. Thermal treatments modify the CL spectra and such changes are considered the result of valence of aggregation states of the tin impurities.