Acquisition of pure-phase diffusion spectra using oscillating-gradient spin echo |
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Authors: | Momot Konstantin I Kuchel Philip W Chapman Bogdan E |
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Institution: | School of Molecular and Microbial Biosciences, University of Sydney, NSW 2006, Australia. konstantin@usyd.edu.au |
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Abstract: | Oscillating-gradient spin echo (OGSE) diffusion experiments have long been used to measure the short-time apparent diffusion coefficient, D(app)(t), in the presence of restricted diffusion, as well as the spectrum of the slow-motion velocity autocorrelation function. In this work, we focus on two previously unexplored aspects of OGSE experiments: convection compensation and acquisition of pure-phase diffusion spectra in the presence of homonuclear scalar couplings. We demonstrate that convection compensation afforded by single-echo OGSE compares well with that in double-echo convection-compensated PGSE experiments. We also show that, in the presence of homonuclear scalar couplings, setting the OGSE echo time to 1/2J enables acquisition of pure-phase diffusion spectra and yields more reliable D estimates than mixed-phase PGSE or OGSE spectra. Pure-phase OGSE acquisition is also compatible with measurements of the apparent diffusion coefficient at an arbitrary diffusion time. These features of OGSE can be valuable in diffusion measurements of scalar-coupled small-molecule probes in cellular and other heterogeneous systems. |
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Keywords: | Convection compensation NMR diffusion and flow measurements Modified-cosine gradient pulse Apparent diffusion coefficient Homonuclear scalar couplings |
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