Estimation of the Characteristic Length Scales forB0Variation Using the OE-CTPG Pulse Sequence
✍ Scribed by Mark A. Horsfield; Simon A. Clark; Timothy J. Norwood
- Book ID
- 102594001
- Publisher
- Elsevier Science
- Year
- 1996
- Tongue
- English
- Weight
- 178 KB
- Volume
- 122
- Category
- Article
- ISSN
- 1064-1858
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✦ Synopsis
NMR measurement of diffusion is a well-established tool for of increasing gradient strength. When diffusion is uninvestigating the microstructure of heterogeneous materials. Since restricted (i.e., when there is no impedance to the random an applied magnetic-field gradient is an essential element of the motion of the molecules), the measured value of the diffupulse sequences usually used, any magnetic-field gradients present sion coefficient is independent of the diffusion time. Howwithin the sample may interfere with the NMR measurement, in ever, if there is a barrier to the diffusing molecules' motions, some cases making it impracticable. Here, a method that uses the such as cell walls in biological tissue or the grain surface in internal gradients themselves to provide information about the porous rock, the apparent value of the diffusion coefficient heterogeneous structure, in materials where these gradients are will decrease with increasing diffusion time. From the variastrong, is described. The technique is demonstrated using a range tion of the value of the apparent diffusion coefficient with of solvents in packs of different sizes of glass beads. ᭧ 1996 Academic diffusion time it is often possible to obtain quantitative infor-Press, Inc.
mation about the restricting barrier, for example, cell size and cell wall permeability in the case of biological tissue, and pore size and interconnectedness in the case of rock.