Dependence of plasmonic properties on electron densities for various coupled Au nanostructures

Chihao Liow, Fanben Meng, Xiaodong Chen, Shuzhou Li

Research output: Contribution to journalArticlepeer-review

16 Scopus citations

Abstract

Noble metallic nanostructures have great potential in optical sensing application in visible and near-infrared frequencies. Their plasmonic properties can be manipulated by in situ controlling their electron densities for isolated nanostructures. However, the effect of charging remains underexplored for coupled systems. In this work, we theoretically investigated the dependence of their far-field and near-field properties on their electron densities for various coupled gold structures. With increasing electron densities, their enhancement factors increase while their plasmonic resonance peaks are blue-shifted. The resonance peak position of ellipsoid-ellipsoid dimers shows the highest sensitivity in response to the charging effects with the slope of -2.87. The surface-averaged electric field of ellipsoid monomer shows largest enhancement ratio of 1.13 with 16% excess electrons. These results can be well explained by an effective dipole moment model. In addition, we also studied the sphere-on-substrate nanostructure which can be precisely fabricated. This system shows low sensitivity to the charging effect with the slope of -1.46 but remarkable enhancement ratio of 1.13 on near field response with 16% excess electrons. (Graph Presented).

Original languageEnglish (US)
Pages (from-to)27531-27538
Number of pages8
JournalJournal of Physical Chemistry C
Volume118
Issue number47
DOIs
StatePublished - Nov 26 2014

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