Long-Wavelength Transverse Modes in Charged Colloidal Crystals

Abstract

The dynamics of closely index matched colloidal crystals of charged silica spheres dispersed in deionized ethylene glycol-water mixture is investigated using dynamic light scattering. At variance with the reports of phonon dispersion measurements on thin colloidal crystals, our observations on millimeter-sized crystals show unambiguous evidence for overdamped transverse modes turning propagative in the range of small wave numbers in agreement with the theory of hydrodynamic interactions in charged colloidal crystals.

Anisotropic elasticity of experimental colloidal Wigner crystals

“…More recently, the transition from overdamped to propagating transverse modes in aqueous b.c.c. colloidal crystals was observed for the first time [34]; however, such propagating modes are not observable when the sample dimensions are too small [6,34], as we expect to be the case in our experiments.…”

Anomalous Vibrational Dispersion in Holographically Trapped Colloidal Arrays

“…A crossover from overdamped to underdamped dynamics at large wavelengths has been predicted [10] and recently observed [11] for the transverse lattice vibrations of colloidal crystals. This crossover, however, is governed by direct interparticle interactions rather than by hydrodynamic coupling.…”

“…Related phenomena have been studied in dusty plasmas whose highly charged constituent particles can be harmonically constrained in one or two dimensions by external electric fields [6 -9], and in charge-stabilized colloidal crystals [10,11]. The present system differs from these and most other solids in that cooperativity arises from the spatial dependence of a purely dissipative interaction.…”

Enhanced nonlinear optical responses of materials: Composite effects

“…They exhibit body centered tetragonal (bct), body centered cubic (bcc) and face-centered cubic (fcc) structures, depending on the lattice constants and hence the volume fraction of colloidal particles. These structures can be investigated by using static and dynamic light scattering techniques [45,46]. So far, colloidal-based optical sensors [47] (and photonic-band-gap materials based on inverse opaline structures [48]) have been made possible by these fabrication techniques.…”