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Published on: April 19, 2021
High-resolution NMR spectra in inhomogeneous fields utilizing the CRAZED sequence without coherence selection
Congbo Cai1, Yanqin Lin, Shuhui Cai
1Department of Physics, State Key Laboratory for Physical Chemistry of Solid Surface, Xiamen University, Siming South Road, Xiamen, Fujian 361005, China.
Summary
Coherence selection gradients are not essential for high-resolution NMR spectroscopy in inhomogeneous fields. Appropriate phase cycling allows their omission, simplifying spectral acquisition and analysis.
Area of Science:
- Nuclear Magnetic Resonance (NMR) Spectroscopy
- Magnetic Resonance Imaging (MRI)
Background:
- CRAZED-type sequences are commonly used for high-resolution NMR in inhomogeneous fields.
- Coherence selection gradients are traditionally considered crucial for these sequences.
Purpose of the Study:
- To investigate the necessity of coherence selection gradients in CRAZED-type sequences for high-resolution NMR.
- To explore alternative methods for achieving high-resolution spectra without these gradients.
Main Methods:
- Experimental validation of NMR spectroscopy sequences.
- Application of appropriate phase cycling techniques.
- Analysis of spectral peak linewidth and its dependence on experimental parameters.
Main Results:
- Demonstrated that coherence selection gradients can be omitted in CRAZED-type sequences.
- Showed that spectral linewidth is independent of dipolar correlation distance.
- Identified diffusion and T(2) relaxation as the primary factors affecting linewidth.
Conclusions:
- Challenges the indispensability of coherence selection gradients for high-resolution NMR in inhomogeneous fields.
- Suggests that phase cycling is a viable alternative for gradient omission.
- Recommends a re-evaluation of the underlying mechanisms in iMQC-based high-resolution spectroscopy.
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