Search results for "Forced Rayleigh scattering"

Simultaneous measurement of rotational and translational diffusion by forced Rayleigh scattering. Colloid spheres in suspension

1996

Abstract It is shown that the technique of forced Rayleigh scattering, traditionallyemployed to probe translational diffusion, can be employed to probe rotational diffusion as well. Thus with a single experiment both quantities are measured. The system under investigation is colloid spheres suspended in a glass-forming liquid. Furthermore, it is shown that the Stokes-Einstein and Debye-Stokes-Einstein relations for translational and rotational diffusion, respectively, are valid for spherical colloid particles in a supercooled liquid matrix in the vicinity of the glassy state.

Forced Rayleigh scattering from non-harmonic gratings applied to complex diffusion processes in glass-forming liquids

1999

Abstract Tracer diffusion of 9,10-phenanthrenequinone (PQ) and its photoproduct in super-cooled phenolphthalein-dimethyl-ether (PDE) was studied by forced Rayleigh scattering. In order to investigate the spatial frequency dependence of the grating dynamics, several spatial harmonics of the grating with non-sinusoidal phase profile produced by non-linear recording were monitored. An optical scheme with a diverging reading beam is proposed for simultaneous reconstruction of the harmonic components.

1997

We have determined by forced Rayleigh scattering the diffusion coefficients of photo-labeled polystyrene micronetwork spheres (radii ≤ 10 nm) in melts of linear polyvinylmethylether (M W ≤ 40000 g/mol) at temperatures of 20-80°C. An expected slippage of the spheres through the meshes of the entanglement network appears possible but is still within the experimental uncertainty of our results.

Probing Poly(n-butyl-methacrylate) Latex Film via Diffusion of Hydrophilic and Hydrophobic Dye Molecules

2003

In the study of holographic grating relaxation (forced Rayleigh scattering, FRS) in nascent latex films we examined poly(n-butyl methacrylate) films using two complementary diffusing probes:  a hyd...

Dynamics of Copolymer Micelles in a Homopolymer Melt:  Influence of the Matrix Molecular Weight

2000

We have studied the dynamics of styrene−isoprene (SI) block copolymer micelles in a matrix of linear entangled polyisoprene (PI) chains, using forced Rayleigh scattering (FRS) and dynamic mechanica...

Tracer diffusion in polymer and organic liquids close to the glass transition studied by forced rayleigh scattering

2007

Translational diffusion coefficients D of photochronic dye molecules have been measured by forced Rayleigh scattering in polymer diluent systems at compositions from pure polymer to pure diluent. D could be measured down to below the glass transition temperature T g. In the pure diluent, D(T g) was found typically about two decades below that in the pure polymer but still far above the Stokes-Einstein prediction extrapolated from high temperatures. Some experimental results are in contrast with predictions from free-volume theory.

Applications of “Forced Rayleigh Scattering” and “Photon Correlation Spectroscopy” for the examination of transport properties in polymer melts

2007

The importance of optical techniques for the characterization of the dynamics in polymers has increased in the last 10 years. This was caused by the rapid development in optics and microelectronics which has made these techniques easily available and extremely precise. However, in case of the examination of transport properties in bulk polymers, new difficulties arise due to the comparably slow dynamics underlying these phenomena. The topic of this paper is a small survey of two optical techniques which can be applied to solve the arising problems and a presentation of some results of our working group concerning slow translational transport processes in polymers. In a first part, the techn…