Open Access Nano Express

Accurate Computation of Electric Field Enhancement Factors for Metallic Nanoparticles Using the Discrete Dipole Approximation

A Eugene DePrince12 and Robert J Hinde1*

Author Affiliations

1 Department of Chemistry, The University of Tennessee, Knoxville, TN, 37996-1600, USA

2 Department of Chemistry, The University of Chicago, Chicago, IL, 60637, USA

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Nanoscale Research Letters 2010, 5:592-596  doi:10.1007/s11671-009-9511-7

Published: 29 January 2010

Abstract

We model the response of nanoscale Ag prolate spheroids to an external uniform static electric field using simulations based on the discrete dipole approximation, in which the spheroid is represented as a collection of polarizable subunits. We compare the results of simulations that employ subunit polarizabilities derived from the Clausius–Mossotti relation with those of simulations that employ polarizabilities that include a local environmental correction for subunits near the spheroid’s surface [Rahmani et al. Opt Lett 27: 2118 (2002)]. The simulations that employ corrected polarizabilities give predictions in very good agreement with exact results obtained by solving Laplace’s equation. In contrast, simulations that employ uncorrected Clausius–Mossotti polarizabilities substantially underestimate the extent of the electric field “hot spot” near the spheroid’s sharp tip, and give predictions for the field enhancement factor near the tip that are 30 to 50% too small.

Keywords:
Metallic nanoparticles; Optical properties; Simulation