Spin-lattice relaxation in a system governed by diffusion
Abstract
The physical and mathematical formulation of the "two-fraction fast-exchange" model is investigated. A region R containing spins within which these spins migrate via diffusion and also decay (flip) is considered. These decay rates are position dependent; both volume-like and surface-like subregions, in which there is spin decay are dealt with. A general integral theorem, based on the diffusion equation, is presented which enables one to calculate approximately the time-dependent overall magnetization for the region R. In the high-diffusivity limit (fast-exchange) it is shown that this time dependence is that of a single exponential decay. The two-fraction fast-exchange situation emerges as an appropriate special case.
- Publication:
-
Journal of Magnetic Resonance
- Pub Date:
- 1977
- DOI:
- 10.1016/0022-2364(77)90230-X
- Bibcode:
- 1977JMagR..26...17B