Investigation of intermolecular double-quantum off-resonance longitudinal relaxation in the tilted rotating frame

A method for longitudinal relaxation time measurement in inhomogeneous fields

The spin-lattice relaxation time (T₁) plays a crucial role in the study of spin dynamics, signal optimization and data quantification. However, the measurement of chemical shift-specific T₁ constants is hampered by the magnetic field inhomogeneity due to poorly shimmed external magnetic fields or intrinsic magnetic susceptibility heterogeneity in samples. In this study, we present a new protocol to determine chemical shift-specific T₁ constants in inhomogeneous fields. Based on intermolecular double-quantum coherences, the new method can resolve overlapped peaks in inhomogeneous fields. The measurement results are in consistent with the measurements in homogeneous fields using the conventional method. Since spatial encoding technique is involved, the experimental time for the new method is very close to that for the conventional method. With the aid of T₁ knowledge, some concealed information can be exploited by T₁ weighting experiments.