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Light Scattering

S. Wiegand, P. Lang, J. K. G. Dhont (Soft Condensed Matter), and Helge Klemmer (Physical Chemistry)

This course will give an overview over light scattering techniques in complex soft matter, which are useful to study polymer solutions, suspensions of synthetic and biological colloids, and microemulsions. After an introduction to dynamic and static light scattering techniques in the bulk phase, we will investigate the dynamics of the solute particles close to a wall by evanescent wave scattering and in nonequilibrium in a temperature gradient using a thermogravitational column and interferometric detection. To gain understanding of the interaction between a colloidal particle and the wall, the interaction potential will be determined by total internal reflection microscopy. After the course, participants should have gained a basic knowledge in static and dynamic light scattering and understand how the dynamics of the systems changes in the “external fields” confinement and temperature.

The five-day course takes place on March 10-14 in the Institute for Physical Chemistry at Universität zu Köln and in the Institute for Soft Condensed Matter at Foschungszentrum Jülich from 9:00am until 5:00pm. Please register until March 2 by email to biosoft@fz-juelich.de. The participation of interested PhD students that are not a fellow of the IHRS BioSoft will be confirmed on March 3 subject to availability of places.

Experiments:
Two days in Cologne:
1) Dynamic and Static light scattering on colloids and microemulsions (2 days)
- Basic Theory
- The students will measure the size of model particles and will determine the effect of particle number density, polydispersity and modality by means of DLS and SLS. (1 day)
- Using a temperature sensitive microemulsion, the effect of variable structures (sphere to cylinder to network) on the scattering behavior will be determined. (1 day)

Three days in Juelich:
1) Thermogravitational column (TGC) to measure transport in temperature gradients (1 day):
- Basic theory
- The students will measure the temperature variation of the refractive index of a binary mixture by means of interferometry
- A TGC measurement will be performed together with the student, and the students will analyze the data to determine the thermodiffusion coefficient of the mixture.

2) Evanescent Wave Scattering (EWS) and Total Internal Reflection Microscopy (TIRM) to characterize diffusion near a wall and measure interactions of colloids with a wall (2 days):
- Basic theory
- The students will measure the interaction potential of charged colloids with a charged wall with TIRM
- The students will measure the diffusion coefficient by standard dynamic light scattering.
- The supervisor will perform an EWS experiment, and the students will analyze the data to determine diffusion coefficients near the wall.

Additional Information

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