Figure 14.

¹H resolution as a function of degree of sample or structural inhomogeneity (Δ^inhom). Total effective linewidth, Δ^tot (solid curves), is simulated for a range of MAS frequencies using eq 11, assuming the inhomogeneous contribution of 0.2, 0.15, 0.10, and 0.05 ppm (black, red, green, and blue solid and dashed curves, respectively), and the homogeneous contribution as determined experimentally for ν_r = 40–111 kHz for a representative amide ¹H of residue T11 in nondeuterated GB1 on 23.5 T (a) and 11.75 T (b) spectrometers. The x-axis is linear with rotor period. Note that despite a generally lower absolute linewidth (in Hz) on a 500 MHz ¹H spectrometer (b) for ν_r > 60 kHz, the actual resolution in ppm (second vertical axes) is inferior compared to that of a 23.5 T spectrometer (a).