Depth profile of tin in float glass - a CEMS study

The tin content of the bath side of float glass was studied by CEMS (conver sion electron Mossbauer spectroscopy). The method provides a high surface s ensitivity with an information depth of 1 mu m, and allows a distinction be tween the different valence states of tin. Depth profiles were measured by etching samples stepwise. The tin content decreases rapidly from the surfac e to the bulk and shows the typical hump between 5 and 10 mu m. Sn2+ domina tes at the surface, but close to the hump, Sn4+ clearly prevails. Still dee per inside, the lower valence states become visible, until the tin concentr ation falls below the sensitivy limit.