Fig. 3.

Dependence of sin² θ _eff on the spin-lock amplitude ω₁ for different sweep ranges ν _sweep (solid lines: 2 kHz, dashed lines: 4 kHz, dotted lines: 10 kHz). The black lines result from a resonance with a chemical shift in the middle of the sweep, and the red lines have a relative shift of 10 ppm with respect to the middle of the sweep. The effect of the offset of the resonance vanishes at larger sweep widths (10 kHz). The difference in sin² θ _eff between the resonances with the different chemical shifts is indicated as a grey shaded area