arXiv subjects

Hans Hennig von Gruenberg

Publications and source records attributed to Hans Hennig von Gruenberg.

2 recordsLinked to original sources

arXiv2008

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

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.

cond-mat.other↗

arXiv2003

On the nature of long-range contributions to pair interactions between charged colloids in two dimensions

We perform a detailed analysis of solutions of the inverse problem applied to experimentally measured two-dimensional radial distribution functions for highly charged latex dispersions. The experiments are carried out at high colloidal densities and under low-salt conditions. At the highest studied densities, the extracted effective pair potentials contain long-range attractive part. At the same time, we find that for the best distribution functions available the range of stability of the solutions is limited by the nearest neighbour distance between the colloidal particles. Moreover, the measured pair distribution functions can be explained by purely repulsive pair potentials contained in the stable part of the solution.

cond-mat.soft↗