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

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.Financial support from the Portuguese Foundation for Science and Technology (FCT) through Project PTDC- FIS-113199-2009 is gratefully acknowledged