Is it possible to assess spatial correlations in a system of polarizable particles by measuring its optical response?

Abstract

Optical response of a system of (nearly) identical polarizable particles, coupled by electromagnetic interactions is studied theoretically addressing the following question: Is it possible to extract information concerning the spatial correlations in the particles' positions from the experimentally measurable optical response of the system? The relation between the spectral-dependent solutions of the coupled-dipole equations and the type and parameters of the particle-particle correlation function in real space is analyzed. The physical system considered is a collection of metallic nanoparticles distributed over a square or cubic lattice in a random-correlated way, relevant to metal- dielectric composites interesting for nanoplasmonics. We show that it is possible to propose a numerical criterium that allows for conclusion concerning the degree of correlation in the particle positions using the (experimentally measurable) extinction spectrum of the system.