Université de Fribourg

Improved diffusing wave spectroscopy based on the automatized determination of the optical transport and absorption mean free path

Zhang, Chi ; Reufer, Mathias ; Gaudino, Danila ; Scheffold, Frank

In: Korea-Australia Rheology Journal, 2017, vol. 29, no. 4, p. 241–247

Diffusing wave spectroscopy (DWS) can be employed as an optical rheology tool with numerous applications for studying the structure, dynamics and linear viscoelastic properties of complex fluids, foams, glasses and gels. To carry out DWS measurements, one first needs to quantify the static optical properties of the sample under investigation, i.e. the transport mean free path l* and the...

Université de Fribourg

Charactrisation of particle assemblies by 3D cross correlation light scattering and diffusing wave spectroscopy

Scheffold, Frank

In: SPIE Proceedings, 2014, vol. 9232: International Conference on Optical Particle Characterization (OPC 2014), p. 923203–923203–4

To characterize the structural and dynamic properties of soft materials and small particles, information on the relevant mesoscopic length scales is required. Such information is often obtained from traditional static and dynamic light scattering (SLS/DLS) experiments in the single scattering regime. In many dense systems, however, these powerful techniques frequently fail due to strong multiple...

Université de Fribourg

Modulated 3D cross-correlation light scattering: Improving turbid sample characterization

Block, Ian D. ; Scheffold, Frank

In: Review of Scientific Instruments, 2010, vol. 81, no. 12, p. 123107

Accurate characterization using static light scattering (SLS) and dynamic light scattering (DLS) methods mandates the measurement and analysis of singly scattered light. In turbid samples, the suppression of multiple scattering is therefore required to obtain meaningful results. One powerful technique for achieving this, known as 3D cross-correlation, uses two simultaneous light scattering...

Université de Fribourg

Scattering information obtained by optical microscopy: Differential dynamic microscopy and beyond

Giavazzi, Fabio ; Brogioli, Doriano ; Trappe, Véronique ; Bellini, Tommaso ; Cerbino, Roberto

In: Physical Review E, 2009, vol. 80, no. 3, p. 031403

We describe the use of a bright-field microscope for dynamic light scattering experiments on weakly scattering samples. The method is based on collecting a time sequence of microscope images and analyzing them in the Fourier space to extract the characteristic time constants as a function of the scattering wave vector. We derive a theoretical model for microscope imaging that accounts for (a) the...

Université de Fribourg

Oil-continuous microemulsions mixed with an amphiphilic graft copolymer or with the parent homopolymer. Polymer–droplet interactions as revealed by phase behavior and light scattering

Holmberg, Anna ; Piculell, Lennart ; Schurtenberger, Peter ; Olsson, Ulf

In: Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2004, vol. 250, p. 325-336

Polymer–droplet interactions have been studied in AOT/water/isooctane oil-continuous microemulsions mixed with an amphiphilic graft copolymer, or with the parent homopolymer (AOT = sodium bis(2-ethylhexyl) sulfosuccinate). The graft copolymer has an oil-soluble poly(dodecyl methacrylate) backbone and water-soluble poly(ethylene glycol) side chains. Pseudo-ternary polymer/droplet/isooctane phase...