Metal-insulator nanocomposites which act optically like homogeneous conductors

College

College of Science

Department/Unit

Physics

Document Type

Archival Material/Manuscript

Publication Date

2007

Abstract

Conductor-insulator nanocomposites in which the conductor percolates can have optical responses at longer wavelengths like dense conductors with an effective plasma frequency omega(*)(p). This applies at wavelengths where the Bergman spectral function F for permittivity varies sufficiently slowly with wavelength omega(*)(p) can be engineered by varying the components, the nanostructure's topology, or the dielectric volume fraction f. The homogenized conductor acts like a dense conductor whose charge carriers have effective mass m(eff)(*). Results are presented for omega(*)(p)(f) and m(eff)(*)(f) using the Maxwell Garnett (MG) and Bruggeman (BR) models for spheres and aligned ellipsoids. In the BR case m(eff)(*)(f) at the percolation concentration is singular. Example omega(*)(p) data for spheres and ellipsoids are given which match predictions. Anisotropy in effective mass is considered, such that effective plasma frequency can depend strongly on polarization direction of incident light.

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Disciplines

Physics

Keywords

Gold—Surfaces—Optical properties; Mesoporous materials—Surfaces—Optical properties; Surface plasmon resonance

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