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A combination of the spatially- and temporally-resolved phonon spectroscopies has enabled calibration of hydrogen bond transition from the vibration mode of heavy water to the core-shell structured nanodroplets and to the ionic hydration shells of salt solutions in terms of phonon abundance-lifetime-stiffness. It is uncovered that charge injection by salt solvation and skin formation by molecular undercoordination (often called confinement) share the same supersolidity characterized by H–O (D–O as a probe) bond contraction, O:H nonbond elongation, and polarization. Such a process of bond transition stems the solution viscosity, surface stress, and slowing down of the molecular dynamics and diffusivity. The nanodroplet skin reflection further hinders phonon energy dissipation associated with longer D–O phonon lifetime. Financial support received from National Natural Science Foundation of China (Nos. 11872052(YL); 21875024(CQ)), the Science Challenge Project (No. TZ2016001) of China is acknowledged.

From the perspective of O:H-O bond cooperativity, we analyzed the solute capability of transiting the O:H-O bond from the mode of ordinary water to the hydration state and its consequence on the solution viscosity and surface stress. Phonon spectrometric results suggest that glycine and its N-methyl derivatives strongly affect the surrounding solvent molecules through H ↔ H repulsion and dipolar polarization. The H ↔ H interproton repulsion disrupts the surface stress, and the polarization enhances the solution viscosity.

An incorporation of the hydrogen bond (O:H O or HB) cooperativity notion, contact angle detection, and the differential phonon spectrometrics (DPS) has enabled us to gain refined information on the HCl, KCl and KOH solvation resolved solute-solvent molecular interactions and the solution surface stresses. Results show that ionic polarization stiffens the solvent H O bond phonon from 3200 to 3480 cm −1 in the hydration shells. The HO − in alkaline solution, however, shares not only the same H O phonon redshift of compressed water from 3200 to −1 but also the dangling bonds of H 2 O surface featured at 3610 cm −1 . Salt and alkaline solvation enhances the solution surface stress by K + and Cl − ionic polarization. The excessive H + proton in acid solution forms a H↔H anti-HB that depresses the solution surface stress, instead. The solute capability of transforming the fraction of the O:H O bonds of the solvent matrix is featured by: f H = 0 and f x ∝ 1-exp(-C/C 0 ) (x = HO − , K + and Cl − ) towards saturation. Exercises not only confirm the presence of the H↔H anti-HB point fragilization, the O:⇔:O super-HB point compression, and ionic polarization dominating the performance of the respective HCl, KOH, and KCl solutions, but also demonstrate the power of the DPS that enables high resolution of solute-solute-solvent interactions and correlation between HB relaxation and solution surface stress.