Fig. 2. Nonspecific long-range changes in the H-bond network of water.

(A) fs-ESHS intensities, relative to that of pure water, of 21 different electrolyte solutions obtained at a scattering angle of 90^o (P_outP_inP_in polarization combination). The relative intensities of all electrolyte solutions can be fitted with the same equation. The dashed line indicates the concentration of half saturation. fs-ESHS intensities for CCl₄ are also plotted [the x axis should be read here as “Concentration (μM)”]. (B) fs-ESHS intensities of NaCl in H₂O and D₂O (P_outP_inP_in polarization combination). (C) Water-water orientational correlations (left) and corresponding changes in average tilt angles (right) obtained from a molecular dynamics simulation of pure water. (D) Ion-induced change in the orientational order for an 8 mM NaCl solution. Changes in the distance-weighed water-water orientational correlations are shown (left axis), as well as the corresponding changes in the distance-weighted average tilt angle per water molecule (right axis).