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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 16: Poster: Colloids and Complex Liquids

CPP 16.34: Poster

Dienstag, 27. März 2012, 18:15–20:45, Poster A

Analyzing polydispersity and deformation in confocal images of colloids — M. Roth, J. Wenzl, M. Franzmann, and •G. K. Auernhammer — MPI Polymer Research, Mainz, Germany

Confocal microscopy has been used to study the dynamical and structural properties of colloidal and granular matter. Three dimensional positions and translational motions of the constituent particles can be measured with high precision. Other quantities like forces or rotational motions, or the analysis of polydisperse samples, are harder to address.

Forces between particles in contact lead to deformations of the particles. For soft hollow spheres these deformations are large enough to be identified from confocal images. We present an extension to the algorithm by Crocker and Grier [1] to automatically extract the deformation particles (absoltute values and orientation) and thus forces on the particle. For this we use colloids that are only labelled in their surface. Convoluting the image of deformed hollow spheres with the expected image of the undeformed state leads to a correlation peak that carries the information about the deformation [2].

Additionally we show how to detect reliably the coordinates of polydisperse colloids in confocal images. We develop methods to reliable measure the position and extension of spherical particles. To illustrate the applicability of this algorithm we show the restructuring of colloidal aggregates under mechanical stress.

[1] J. C. Crocker and D. G. Grier, J. Coll. Int. Sci., 179, 298 (1996).

[2] M. Roth, M. Franzmann, M. D’Acunzi, M. Kreiter, and G. K. Auernhammer, arXiv:1106.3623v1 [cond-mat.soft] (2011).