Raman spectroscopic study of NaNO₃ solution system - solute clustering in supersaturated solutions

Raman spectroscopic studies of NaNO₃ solutions were performed to examine solute clustering in supersaturated solutions. The results suggest that solute clustering occurs in undersaturated, saturated, as well as supersaturated solutions. The solute clusters do not have crystalline structure, rather they are solvated clusters consisting of solute and solvent molecules. There are some indications that, as the solution becomes supersaturated, some of the solute clusters coalesce into larger clusters with consequent dilution of other clusters and lower-ordered species. Current results suggest that the mechanisms governing crystallization from solution are associated with the coalescence of solvated solute clusters and/or changes in their properties and structures.