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ESR measurement of translational diffusion constants
Author(s) -
Fawthrop Susan A.,
Gillies Duncan G.,
Sutcliffe Leslie H.,
Symms Mark R.
Publication year - 1995
Publication title -
magnetic resonance in chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.483
H-Index - 72
eISSN - 1097-458X
pISSN - 0749-1581
DOI - 10.1002/mrc.1260331317
Subject(s) - chemistry , diffusion , gaussian , sampling (signal processing) , fick's laws of diffusion , measure (data warehouse) , constant (computer programming) , computational physics , analytical chemistry (journal) , biological system , nuclear magnetic resonance , optics , thermodynamics , computational chemistry , physics , chromatography , database , detector , biology , computer science , programming language
ESR spectroscopy can be used to measure the translational diffusion constants of spin probes in a variety of media using a capillary method. Following preliminary work, it has been possible to improve upon the accuracy of determining diffusion constants in two ways. Both methods require an experimental measurement of the resonant cavity sampling profile. In the first procedure, this cavity profile is convolved with a trial Gaussian distribution and the result is compared with the experimental data obtained from the ESR measurements; the diffusion constant is then determined by graphical optimization. The second method is a graphical one based on a knowledge of the experimental diffusion profile and the cavity sampling profile. Both methods have been shown to give similar results but the second less rigorous corrected‐zero method is generally simpler to apply. For a medium such as water, it takes several days to acquire the necessary experimental data but the time taken to carry out the experiment can be shortened (or slower rates of diffusion can be measured) by using a shielded resonant cavity.