Diffusion NMR for Determining the Homogeneous Length-Scale in Lamellar Phases.
Author
Summary, in English
The size of the anisotropic domains in a lyotropic liquid crystal is estimated using a new protocol for diffusion NMR. Echo attenuation decays are recorded for different durations of the displacement-encoding gradient pulses, while keeping the effective diffusion time and the range of the wave vectors constant. Deviations between the sets of data appear if there are non-Gaussian diffusion processes occurring on the time-scale defined by the gradient pulse duration and the length-scale defined by the wave vector. The homogeneous length-scale is defined as the minimum length-scale for which the diffusion appears to be Gaussian. Simulations are performed to show that spatial variation of the director orientation in an otherwise homogeneous system is sufficient to induce non-Gaussian diffusion. The method is demonstrated by numerical solutions of the Bloch-Torrey equation and experiments on a range of lamellar liquid crystals with different domain sizes.
Department/s
Publishing year
2008
Language
English
Pages
2782-2794
Publication/Series
The Journal of Physical Chemistry Part B
Volume
112
Issue
10
Document type
Journal article
Publisher
The American Chemical Society (ACS)
Topic
- Physical Chemistry
Status
Published
ISBN/ISSN/Other
- ISSN: 1520-5207