On the lack of capillary Mössbauer spectroscopic effect for SnII-containing aqueous solutions trapped in corning Vycor ‘thirsty’ glass

Liquids trapped in the pores of certain silicate glasses (such as Corning Vycor ‘thirsty’ glass) were found to display frozen solutions like behavior at temperatures much higher than their actual freezing point. For example, recoilless γ-resonance absorption was observed for Mossbauer active solutes such as 119Sn and 57Fe salts at room temperature (i.e., without the need of quenching). Thus capillary Mossbauer spectroscopy (CMS) proved to be a new and useful experimental tool with great potential in solution chemistry. As part of a research project concerned with the hydrolysis of SnII salts, we attempted to perform 119Sn CMS measurements for solutions containing stannous ion in a range of aqueous environments. Somewhat surprisingly, we found that under ambient conditions, SnII aqueous liquid solutions, both the acidic and the basic systems, are essentially CMS-silent. This can be attributed to the strong temperature dependence of Lamb–Mossbauer factor of SnII species, which may result in the complete disappearance of Mossbauer pattern well below room temperature. These observations can also explain why previous publications concerned with the use of CMS dealt exclusively with SnIV and not with SnII containing liquids.