Vibration spectroscopy of weakly interacting mesoscopic colloids

• DOI: 10.1039/c2sm07034k
• Publication Date: 2012-02-29T15:30:36Z
• Authors: Maurizio Mattarelli; Maurizio Montagna; Tim Still; Dirk Schneider; George Fytas
• Keywords: Mesoscopic physics; Particle (ecology); Hard spheres; Brillouin zone; Polystyrene

Brillouin spectroscopy has been used to study the vibrational dynamics of clusters spherical polystyrene (PS) particles with different size. In a first approximation, spectra can be described by single particle model within continuum approximation Lamb theory. The yields excellent results for diameter d ≳ 500 nm, but fails in accounting lineshapes observed lowest frequency signals vibration spectrum smaller due broadening and shift lines confined vibrations. also predict an additional very low broad band case small (d ≲ 400nm). This is attributed phonon propagation multiple-particle governed interactions among particles. These produce extended modes close relation sphere. A simple interaction allows represent new spectral features estimate strength long wavelength longitudinal velocity colloidal clusters. Their thermal annealing near glass transition PS enhances which are manifested bands associated vibrations individual spheres. emerging becomes sensitive tool colloids' thermo-mechanical properties as well their interactions.