Hydration-Shell Vibrational Spectroscopy of Water-Mediated Interactions

The hydration-shell surrounding aqueous molecular and ionic solutes may be used to probe solute-induced perturbations in water structure and how that structure changes upon solute aggregation. Thus, hydration-shell vibrational spectra obtained using Raman spectroscopy multivariate curve resolution (Raman-MCR) may be used to probe the structure and temperature dependence of hydrophobic hydration-shells, as well as hydrophobic interactions, ion-pairing, and ion-molecule interactions. Water typically shields all such interactions, including the interactions between oily molecules in water, which are found to be weaker than the corresponding interactions in the absence of water, although open questions remain regarding how these interactions depend on solute size and charge.