Dynamic Electric Response of Charged Fibrous Virus (fd) Suspensions: Interactions of Charged Colloidal Rods in AC

The electric response of charged fibrous viruses (fd), as charged

colloidal rods, to an AC external electric field is explored. Various

field-induced phases and dynamical states are characterized in the

field-amplitude versus frequency plane. The observed phase/state

transitions are due to intercolloidal field-induced interactions as a

result of polarization of double layers and/or the layer of condensed

ions, and possibly electro-osmotic flow. The concentration of fd-

virus is chosen within the isotropic-nematic coexistent phase at a

low ionic strength. For low frequencies, chiral-nematic phases and

dynamical states are induced on increasing the field amplitude. At

high frequencies, (above ∼1 kHz), a uniform homeotropic phase is induced, wherein the fd-rods align along the electric field. Also,

electrode polarization is described in order to correct applied

field amplitudes to obtain the field amplitudes within the bulk

of the suspensions, away from the electrodes. Field-induced non-

equilibrium criticality is experimentally measured.