Correlation between spectral properties and optical basicity for oxide gels doped with chromium(II) ions.

For oxide xerogels of the types: Na/sub 2/O-B/sub 2/O/sub 3/-SiO/sub 2/ and SiO/sub 2/-TiO/sub 2/ prepared by the sol-gel procedure a correlation between one of the absorption bands of Cr/sup 3+/ ion (attributed to the /sup 4/A/sub 2g/(F) to /sup 4/T/sub 2g/(F) transition) and theoretical optical basicity has been found. The experimental results show that Cr/sup 3+/ ion can play the role of basicity probe in the Lewis sense for oxide xerogels. Additionally, its band position can be a relative measure of water content in the same material.