Tilt angle dependence of cross-relaxation in off-resonance ROESY
Cutting, B.; Ghose, R.; Bodenhausen, G.
Journal of Magnetic Resonance 138(2): 326-329
We present an efficient experimental method to evaluate whether the effective cross-relaxation rate between a pair of spins vanishes when applying an off-resonance spin-lock field. It is shown that the cross-relaxation rate can be made to vanish even when the two spins concerned resonate at different offsets and experience significantly different tilt angles of their respective spin-lock fields. This is verified experimentally using a sample of 15N-labeled human ubiquitin, through selective excitation of chosen amide protons. The results are relevant for the quantitative interpretation of off-resonance ROESY experiments.