Seminar: Depth Resolved Dynamics Studied with NSE under Grazing Incidence: Surface Influence on Membrane Fluctuations

Microemulsions near planar hydrophilic surfaces are ordered lamellar, while the bulk structure is bicontinuous. This has been proven with grazing incidence small angle neutron scattering measurements (GISANS), neutron reflectometry, and computer simulations  [1]. The GISANS studies have been extended in the present work to neutron spin echo experiments under grazing incidence (GINSES – Grazing Incidence Neutron Spin Echo Spectroscopy). By varying the incident angle and the overall contrast of the liquid against the solid, the penetration depth of the evanescent wave has been tuned between ~40  - 100 nm. The dynamics of the surfactant membrane of the microemulsion could be studied with this setup as a function of the distance to the hard wall.  It was found that the characteristic relaxation time of the membrane undulations decreases close to the hard surface. This effect is interpreted as a modified dispersion relation of the undulation spectrum of the membrane due to the confining wall. The depth resolved dynamic measurements on the nanosecond scale are the first of its kind.

[1] M. Kerscher et al., Phys. Rev. E 83 030401(R) (2011)

Date

30.01.2012

Time

14:45–15:45

Place

Physics HS3

Garching, Garching, Deutschland

Speaker

Dr. O. Holderer, Juelich Centre for Neutron Science (JCNS)

Organizers

TUM/FRM II

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