FIGURE 2.

Viscosity dependence of ²³Na NMR in glycerol‐water mixtures containing 100 mM NaCl solution. (a) ²³Na signal intensity recovery following 180° inversion, showing faster recovery at higher glycerol concentrations. (b) Viscosity dependence of ²³Na longitudinal relaxation (R ₁) obtained from inversion‐recovery data, shown along with the ²³Na resonance linewidth and the H2¹⁷O R ₁ rates (secondary axis). (c) Relative change in ²³Na linewidth and R ₁ rates or H2¹⁷O R ₁ rates versus relative viscosity, showing the larger sensitivity of ²³Na NMR probes to viscosity variation