Regensburg 2007 – scientific programme
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 7: POSTER: INTERNAL SYMPOSIUM Scattering Experiments
CPP 7.13: Poster
Monday, March 26, 2007, 16:00–18:00, Poster B
Ellipsometric Light Scattering: The Spectroscopic Approach — •Arne Stark1, Andreas Erbe2, Klaus Tauer1, and Reinhard Sigel1 — 1MPI of Colloids and Interfaces, D-14476 Golm — 2Institute of Physics, Academia Sinica, Taiwan
We present first results obtained by Spectroscopic Ellipsometric Light Scattering (SELS). The discussion is complemented by an analysis of the general robustness of ELS against polydispersity effects.
Ellipsometric light scattering is based on Mie theory to analyze the scattering of polarized light by suspended particles in the colloidal range. Similar to standard ellipsometry this technique has an enhanced sensitivity to interface effects, allowing to investigate e.g. (multiple) coatings on particles or adsorbed surface layers.
First experimental results obtained with a multi-wavelength apparatus are presented: augmenting the method to a spectroscopic technique extends the resolution considerably. The camera detector allows a simultaneous investigation of a range of scattering angles and speeds up the measurements. Light of different wavelengths is selected by interference filters from a mercury lamp. Thus, it is established experimentally that coherence of the light source is not required.
All ellipsometric methods yield ratios of eigenvalues of the optical system under investigation. Consequently ELS exhibits an averaging behavior that is distinctly different from normal static light scattering. It is shown theoretically and experimentally that information regarding structural details of the suspended particles is robustly preserved in the presence of moderate sample polydispersity.