Programs in Physics & Physical Chemistry
|[Licence| Download | New Version Template] abne_v1_0.gz(10 Kbytes)|
|Manuscript Title: A Fortran program to interpret pulsed field-gradient spin-echo diffusion data.|
|Authors: E.D. von Meerwall|
|Program title: DIFFUS2|
|Catalogue identifier: ABNE_v1_0|
Distribution format: gz
|Journal reference: Comput. Phys. Commun. 17(1979)309|
|Programming language: Fortran.|
|Computer: IBM 370/158.|
|Operating system: OS/MVS.|
|RAM: 10K words|
|Word size: 32|
|Keywords: Nuclear physics, Molecular, General experiment, Nuclear magnetic Resonance, Spin echo, Pulsed magnetic field Gradient method, Steady gradient method, Science polymer, Diffusion.|
Nature of problem:
NMR spin echo attenuation of the diffusing species, caused by steady and pulsed magnetic field gradients, is interpreted in terms of diffusion constants.
Various least-squares techniques are used to find the diffusion constant, and optionally, the constant spin echo of a non-diffusing species and to detect deviations from the model. Comprehensive error analysis and plot are provided.
The present limit of 40 data points is easily extended.
(1) Three or more data points (spin echo height +- error vs. field gradient pulse length) are required for a least-squares determination of diffusion coefficient;
(2) arbitrary diffusing nuclear species, steady and pulsed field gradients, and rf and gradient pulse timings are accommodated;
(3) non-diffusing nuclear species can be accounted for, and true multi- component diffusion and restricted diffusion can be detected;
(4) a full error analysis coupled with chi-square considerations provides uncertainties of all derived parameters and checks the applicability of the selected model. A plot of data and fit is provided on the line printer.
On the IBM 370/158 III, the program compiles (G1 compiler) in about 6 s CPU; a single case with full analysis takes slightly over 1 s CPU.
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