Dresden 2009 – wissenschaftliches Programm

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DY: Fachverband Dynamik und Statistische Physik

DY 24: Pattern formation in colloidal and granular systems I

DY 24.3: Vortrag

Donnerstag, 26. März 2009, 15:15–15:30, ZEU 255

electric-field induced chiral patterns and dynamical states of fd-virus suspensions — •kyongok kang and jan dhont — forschungszentrum juelich, weiche-materie, juelich, 52425, germany

For low frequency and a low ionic strength, suspensions of fd-virus particles respond to external electric fields due to the deformation of their thick electric double layer. We are interested in pattern formation and phase transitions that results from interactions between such deformed double-layers. Depending on the electric-field amplitude and frequency, dynamical states and various phases are observed. Below a critical frequency, a non-chiral nematic transforms to a chiral nematic with a pitch that is a strong function of the field amplitude and frequency. On increasing the amplitude below a critical frequency, dynamical states are observed where small nematic domains melt and form. These dynamical states are investigated by time-lapsed image correlation function analysis. At sufficiently high frequency, a uniformly aligned phase is stable, which is characterized by means of birefringence measurements. There is a *non-equilibrium critical point* where all transition lines meet, and above which the dynamical state directly transforms to the uniform aligned phase on increasing the frequency.

References: K. Kang, and J. K. G. Dhont, *Double-layer polarization induced transitions in suspensions of colloidal rods*, EPL, 84 (2008) 14005. K. Kang, and J. K. G. Dhont, *Electric-field induced transitions in suspensions of rods (fd-virus) due to double-layer polarization*, Submitted to PRE (2008).