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arXiv · physics/0408003

Propagation of optical excitations by dipolar interactions in metal nanoparticle chains

Abstract

Dispersion relations for dipolar modes propagating along a chain of metal nanoparticles are calculated by solving the full Maxwell equations, including radiation damping. The nanoparticles are treated as point dipoles, which means the results are valid only for a/d <= 1/3, where a is the particle radius and d the spacing. The discrete modes for a finite chain are first calculated, then these are mapped onto the dispersion relations appropriate for the infinite chain. Computed results are given for a chain of 50-nm diameter Ag spheres spaced by 75 nm. We find large deviations from previous quasistatic results: Transverse modes interact strongly with the light line. Longitudinal modes develop a bandwidth more than twice as large, resulting in a group velocity that is more than doubled. All modes for which k_mode <= w/c show strongly enhanced decay due to radiation damping.

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W. H. Weber, G. W. Ford. 2004-09-10. Propagation of optical excitations by dipolar interactions in metal nanoparticle chains. https://doi.org/10.1103/physrevb.70.125429

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