Fig. 10.

Fit of simulated data. Exchange parameters were k _ex = 3,000 s⁻¹, p _b = 0.2, Δω = 3 ppm. Spinlock relaxation rates were generated for a ¹⁵N nucleus at 11.7 and 18.8T, with a 100 ms AFP pulse sweeping over a frequency range of 2,000 Hz in 2,500 steps (ramping 20% at the start and at the end of the pulse). The experimental error in measured rates was set to 0.5 s⁻¹. The left panel shows the (simulated) ‘experimental’ AFP profile (black circles and error bars), superimposed with the individual fits of a Monte Carlo simulation (200 runs) using the Trott-Palmer equation, shown as yellow solid lines. The exchange free profiles for the two field strengths are depicted as dashed black lines. The right panel shows scatter plots of the resulting fit parameters, with the input values at the intersections of the dashed lines. We assumed that cross-correlated relaxation has been corrected for. Further examples (different k _ex and errors) are shown in supplementary material