Fig. 6.

A simulation result using the experimental values of the relaxation times and exchange rates from the T₁-T₂ and T₂-T₂ experiments. The mixing time was t_m = 1, 60 and 200 ms, respectively. In the simulation, a four-site spin system with exchange was assumed. The $T_1^{\mathit{app}}$ and $T_2^{\mathit{app}}$ values were used from those tabulated in Table 1. The nine independent elements in the four by four K̄ matrix were k_α1β =0, $k_{{\alpha }_1\gamma }=\frac{1}{5}{\text{ms}}^{-1},k_{{\alpha }_2{\alpha }_1}=\frac{1}{10}{\text{ms}}^{-1}$, k_α2β =0, $k_{{\alpha }_2\gamma }=\frac{1}{5}{\text{ms}}^{-1},k_{\beta {\alpha }_1}=\frac{1}{100}{\text{ms}}^{-1},k_{\beta \gamma }=\frac{1}{5}{\text{ms}}^{-1}$, k_γα2=0, and k_γβ =0. The disagreement with the experimental results in Fig. 5 shows that not all water molecules in the experiments were exchanging, as discussed in detail in the text. To guide the eye, the dashed lines in the figure represent the location of where T₂ in one dimension is equal to T₂ of the second dimension. The 2D map is shown on a logarithmic scale.