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Although the alcohol-water mixtures are ubiquitously important to beverage and pharmacy industries, it remains yet puzzling how the alcohols interact with watermolecules and how the alcoholmolecules functionalize the hydrogen bond network of liquid water and body fluid. We show spectrometrically that alcohol hydration softens both the H-O bond and the O:H nonbond through hydrogen bond cooperative relaxation and associated charge polarization. Observations suggested that each of the dangling hydroxide group :Ö:H- (interacts with :Ö or -H+) and the dangling methyl group C-H+ (with -H+ or :Ö) is equally capable of interacting with H2O molecules in the form of Ö:↔:Ö point compressor, H+↔H+ point breaker, and O:H-O hydrogen bond at the alcohol-water interface without charge sharing or new bond formation. The alcohol-water O:H-O formation enables the solubility and hydrophilicity of the alcohol; the H+↔H+ breaker embrittles the hydration network; the Ö:↔:Ö compression shortens the O:H nonbond and lengthens the H-O bond. H-O softening is associated with heat emission and depression of solution melting temperature; the O:H nonbond softening (due to polarization) lowers the critical temperatures for freezing. Copyright © 2016 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

The solute-solvent interaction of salts has a striking impact on various biological and industrial processes but its mechanism remains yet mysterious despite intensive studies since 1888 when Franz Hofmeister established the salt series. A combination of confocal Raman spectroscopy and contact angle measurements has enabled us to resolve the hydrogen bond relaxation (O:H-O, HB) and the associated charge polarization dynamics at different molecular site because of alkali halides hydration. Results show consistently that salt hydration softens the O:H phonon but stiffens H-O phonon cooperatively. The extent of HB relaxation and polarization is proportional to the electronegativity difference and ionic radius, following the order of Hofmeister series: X (R/η) = I (2.2/2.5) > Br (1.96/2.8) > Cl (1.81/3.0) > F (1.33/4.0) ≈ 0 for anions, and Y(R/η) = Na (0.98/0.9) > K (1.33/0.8) > Rb (1.49/0.8) > Cs (1.65/0.8) for cations. Observations suggest that ions create each an electric field that aligns, stretches, and polarizes water molecules, which relaxes the O:H-O bond cooperatively, depresses the molecular dynamics, and enhances the hydration shell viscosity and the skin stress. Exercises also demonstrate that Raman spectroscopy performs as a powerful tool for probing the molecular-site-resolved HB network relaxation dynamics in terms of phonon stiffness, molecular fluctuation dynamics, and phonon abundance transition under external stimulus. Copyright © 2016 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]