Use of ultraviolet excitation spectra of Tl+ for probing oxidic networks: alkali-metal borate glasses

Abstract

The use of ultraviolet absorption spectroscopy of p-block s² ions such as Tl⁺ and Pb²⁺ for probing network oxidic media such as glasses and metallurgical slags is reviewed and the limitations of the Tl⁺ probe, owing to gross interference from thallium(III), are highlighted. By contrast, fluorescence spectra of Tl⁺, here reported in lithium, sodium and caesium borate glasses, overcome these limitations. The data are interpreted on the basis of alkali-metal borate glasses providing metal ions with two types of site which differ significantly in basicity. It is shown that the excitation frequencies are signalled by Tl⁺ ions occupying the higher basicity sites.