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arXiv · 0805.1472

Phonon dispersion curves of two-dimensional colloidal crystals: on the wavelength dependence of friction

Joerg Baumgartl·Julian Dietrich·Jure Dobnikar·Clemens Bechinger·Hans Hennig von Gruenberg
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Abstract

Digital video-microscopy measurements are reported of both elastic bandstructures and overdamped phonon decay times in two-dimensional colloidal crystals. Both quantities together allow to determine the friction coefficients along various high symmetry directions in q-space. These coefficients contain valuable information on the hydrodynamic forces acting between the colloidal particles. We find Stokes-like friction for phonons near the edge of the first Brillouin zone and vanishing friction coefficients for long wavelength phonons. The effect of this wavelength dependence in real-space is further investigated by simulating a crystal with constant friction (Langevin simulation) and comparing experimentally measured and simulated particle auto-correlation functions.

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Joerg Baumgartl, Julian Dietrich, Jure Dobnikar, Clemens Bechinger, Hans Hennig von Gruenberg. 2008-05-10. Phonon dispersion curves of two-dimensional colloidal crystals: on the wavelength dependence of friction. https://arxiv.org/abs/0805.1472

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