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. Signals were recorded at temperatures from 40 to 300 K. 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. The CL and waveguide methods are in excellent agreement. Overall, the depth of tin diffusion was up to 8-9 mum in the samples studied. The lifetimes and intensity of the signals are temperature dependent, and these parameters are reported for the 380 nm and 575 nm emission lines. Thermal treatments modify the CL spectra and such changes are considered the result of valence or aggregation states of the tin impurities.