High-resolution NMR spectra in inhomogeneous fields utilizing the CRAZED sequence without coherence selection gradients

Congbo Cai, Yanqin Lin, Shuhui Cai, Zhong Chen, , and Jianhui Zhong

Journal of Magnetic Resonance
Article in Press, Corrected Proof

Abstract: Coherence selection gradients have been considered as indispensable for high-resolution NMR spectroscopy in inhomogeneous fields utilizing the CRAZED-type sequences. However, our experimental results demonstrate that these gradients can be omitted if an appropriate phase cycling is applied. The measured linewidth of reconstructing 1D high-resolution spectral peaks does not depend on the dipolar correlation distance determined by the coherence selection gradients, but is only affected by diffusion and T2 relaxation. This finding suggests the need to reconsider the mechanism for the iMQC-based high-resolution spectroscopy.

Keywords: High-resolution spectra; Intermolecular multiple-quantum coherences; Inhomogeneous fields; Dipolar correlation distance; Coherence selection gradients