NASA Logo

NTRS

NTRS - NASA Technical Reports Server

Back to Results
New techniques for diffusing-wave spectroscopyWe present two new types of measurements that can be made with diffusing-wave spectroscopy (DWS), a form of dynamic light scattering that applies in limit of strong multiple scattering. The first application is to measure the frequency-dependent linear viscoelastic moduli of complex fluids using light scattering. This is accomplished by measuring the mean square displacement of probe particles using DWS. Their response to thermal fluctuations is determined by the fluctuation-dissipation relation, and is controlled by the response of the surrounding complex fluid. This response can be described in terms of a memory function, which is directly related to the complex elastic modulus of the system. Thus by measuring the mean square displacement, we are able to determine the frequency dependent modulus. The second application is the measurement of shape fluctuations of scattering particles. This is achieved by generalizing the theory for DWS to incorporate the effects if amplitude fluctuations in the scattering intensity of the particles. We apply this new method to study the thermally induced fluctuations in the shape of spherical emulsion droplets whose geometry is controlled by surface tension.
Document ID
19950008161
Acquisition Source
Legacy CDMS
Document Type
Conference Paper
Authors
Mason, T. G.
(Princeton Univ. NJ, United States)
Gang, HU
(Princeton Univ. NJ, United States)
Krall, A. H.
(Princeton Univ. NJ, United States)
Weitz, David A.
(Princeton Univ. NJ, United States)
Date Acquired
September 6, 2013
Publication Date
August 1, 1994
Publication Information
Publication: NASA. Lewis Research Center, Second Microgravity Fluid Physics Conference
Subject Category
Inorganic And Physical Chemistry
Accession Number
95N14575
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.
No Preview Available