Self-diffusion measurements with chemical shift resolution in inhomogeneous magnetic fields

Area of Science:

• Nuclear Magnetic Resonance (NMR) Spectroscopy
• Physical Chemistry
• Materials Science

Background:

• Molecular self-diffusion is crucial for understanding chemical and physical processes.
• Accurate measurement of diffusion, especially with chemical shift resolution, is challenging.
• Existing NMR methods may have limitations in diffusion time control and spectral resolution.

Purpose of the Study:

• To develop and demonstrate a novel methodology for chemical shift resolved molecular self-diffusion measurements.
• To enable diffusion measurements in time-independent static and radiofrequency field gradients.
• To overcome limitations of existing techniques for high-resolution "ex situ" NMR.

Main Methods:

• Utilized a stimulated echo sequence with additional z-storage for diffusion encoding.
• Implemented stroboscopic signal acquisition between adiabatic double passages for z-rotation.
• Employed simulations to verify the coherence pathway of the acquired signal.

Main Results:

• Successfully demonstrated the methodology on a mixture of water and isopropanol.
• The pulse sequence allows for diffusion time variation without altering relaxation weighting.
• The technique effectively counteracts phase spread from inhomogeneous static fields.

Conclusions:

• The developed NMR methodology provides chemical shift resolved self-diffusion measurements.
• This technique is suitable for analyzing diffusion in complex mixtures.
• It offers a promising approach for high-resolution "ex situ" NMR studies.