Shape fluctuations and water diffusion in microemulsion droplets: A nuclear spin relaxation study

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Shape fluctuations and water diffusion in microemulsion droplets : A nuclear spin relaxation study. / Carlström, Göran; Halle, Bertil.

I: Journal of Physical Chemistry, Vol. 93, Nr. 8, 01.04.1989, s. 3287-3299.

Forskningsoutput: TidskriftsbidragArtikel i vetenskaplig tidskrift

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TY - JOUR

T1 - Shape fluctuations and water diffusion in microemulsion droplets

T2 - A nuclear spin relaxation study

AU - Carlström, Göran

AU - Halle, Bertil

PY - 1989/4/1

Y1 - 1989/4/1

N2 - Water 2H and 17O spin relaxation data for the microemulsion phase in the AOT/D 2O/isooctane system are reported. The difference between the transverse (R 2) and the longitudinal (R 1) relaxation rates has been measured as function of droplet size, droplet volume fraction, temperature, and resonance frequency. The 2H longitudinal relaxation rate dispersion has been measured over an extensive frequency range, using the field-cycling technique. The focus in the study is on the contribution from slow molecular processes to the quadrupolar relaxation behavior. For the first time in any system, the theoretically predicted relation between the 17O/ 2H ratios of quadrupolar line splittings and of R 2 - R 1 is verified. The extensive experimental data are used to discriminate among three different dynamic models. It is found that water diffusion within the microemulsion droplet cannot account for the experimental data. Instead, a substantial shape polydispersity seems to be required, where at any instant a large fraction of the droplets are nonspherical. However, it is not necessary that the equilibrium shape is nonspherical.

AB - Water 2H and 17O spin relaxation data for the microemulsion phase in the AOT/D 2O/isooctane system are reported. The difference between the transverse (R 2) and the longitudinal (R 1) relaxation rates has been measured as function of droplet size, droplet volume fraction, temperature, and resonance frequency. The 2H longitudinal relaxation rate dispersion has been measured over an extensive frequency range, using the field-cycling technique. The focus in the study is on the contribution from slow molecular processes to the quadrupolar relaxation behavior. For the first time in any system, the theoretically predicted relation between the 17O/ 2H ratios of quadrupolar line splittings and of R 2 - R 1 is verified. The extensive experimental data are used to discriminate among three different dynamic models. It is found that water diffusion within the microemulsion droplet cannot account for the experimental data. Instead, a substantial shape polydispersity seems to be required, where at any instant a large fraction of the droplets are nonspherical. However, it is not necessary that the equilibrium shape is nonspherical.

UR - http://www.scopus.com/inward/record.url?scp=0001724768&partnerID=8YFLogxK

U2 - 10.1021/j100345a080

DO - 10.1021/j100345a080

M3 - Article

VL - 93

SP - 3287

EP - 3299

JO - The Journal of Physical Chemistry Part A: Molecules, Spectroscopy, Kinetics, Environment and General Theory

JF - The Journal of Physical Chemistry Part A: Molecules, Spectroscopy, Kinetics, Environment and General Theory

SN - 1520-5215

IS - 8

ER -