Book contents
- Frontmatter
- Contents
- Preface
- Acknowledgements
- Abbreviations
- 1 Diffusion and its measurement
- 2 Theory of NMR diffusion and flow measurements
- 3 PGSE measurements in simple porous systems
- 4 PGSE measurements in complex and exchanging systems
- 5 PGSE hardware
- 6 Setup and analysis of PGSE experiments
- 7 PGSE hardware and sample problems
- 8 Specialised PGSE and related techniques
- 9 NMR imaging studies of translational motion
- 10 B1 gradient methods
- 11 Applications
- Appendix
- Index
- References
1 - Diffusion and its measurement
Published online by Cambridge University Press: 06 August 2010
- Frontmatter
- Contents
- Preface
- Acknowledgements
- Abbreviations
- 1 Diffusion and its measurement
- 2 Theory of NMR diffusion and flow measurements
- 3 PGSE measurements in simple porous systems
- 4 PGSE measurements in complex and exchanging systems
- 5 PGSE hardware
- 6 Setup and analysis of PGSE experiments
- 7 PGSE hardware and sample problems
- 8 Specialised PGSE and related techniques
- 9 NMR imaging studies of translational motion
- 10 B1 gradient methods
- 11 Applications
- Appendix
- Index
- References
Summary
Introduction
This chapter introduces the concept of diffusion and other associated forms of translational motion such as flow, together with their physical significance. Measurements of translational motion and their interpretation are necessarily tied to a mathematical framework. Consequently, a detailed coverage of the mathematics, including the partial differential equation known as the diffusion equation, is presented. Finally, the common techniques for measuring diffusion are discussed.
Types of translational motion – physical interpretation and significance
‘Diffusion’ is used in the scientific literature with imprecision and ambiguity as there are a number of types of diffusion. With respect to molecular motion, diffusion is used to denote self-diffusion, mutual diffusion and ‘distinct’ (not in the sense of individual to a species) diffusion coefficients. Confusion arises since, although related and having the same units (i.e., m2s−1), these phenomena are physically distinct. The confusion is exacerbated in the NMR literature with the term ‘spin-diffusion’ which is a distinct NMR cross relaxation – based phenomenon involving the random migration of magnetisation via mutual spin flips in neighbouring nuclei, even though it can be measured using techniques related to those outlined in this book. In this book ‘diffusion’ signifies self-diffusion, which will also be referred to as translational diffusion, although some consideration will be given to mutual diffusion since many of the alternative methods for measuring diffusion, especially those based on scattering, provide information on mutual diffusion which is often compared with the results of NMR measurements of translational diffusion.
- Type
- Chapter
- Information
- NMR Studies of Translational MotionPrinciples and Applications, pp. 1 - 68Publisher: Cambridge University PressPrint publication year: 2009
References
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