Plasmonic Properties of Gold Nanoparticles Separated from a Gold Mirror by an Ultrathin Oxide

Syed Mubeen; SHUNPING Zhang; Namhoon Kim; Seungjoon Lee; Stephan Krämer; HONGXING XU; Martin Moskovits

doi:10.1021/nl300351j

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Plasmonic Properties of Gold Nanoparticles Separated from a Gold Mirror by an Ultrathin Oxide

Journal article

Peer reviewed

Plasmonic Properties of Gold Nanoparticles Separated from a Gold Mirror by an Ultrathin Oxide

Syed Mubeen, SHUNPING Zhang, Namhoon Kim, Seungjoon Lee, Stephan Krämer, HONGXING XU and Martin Moskovits

Nano letters, Vol.12(4), pp.2088-2094

2012

DOI: 10.1021/nl300351j

PMID: 22414097

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Abstract

That a nanoparticle (NP) (for example of gold) residing above a gold mirror is almost as effective a surface enhanced Raman scattering (SERS) substrate (when illuminated with light of the correct polarization and wavelength) as two closely coupled gold nanoparticles has been known for some time. (1, 2) The NP-overmirror (NPOM) configuration has the valuable advantage that it is amenable to top-down fabrication. We have fabricated a series of Au-NPOM substrates with varying but thin atomic layer-deposited oxide spacer and measured the SERS enhancement as a function of spacer thickness and angle of incidence (AOI). These were compared with high-quality finite-difference time-domain calculations, which reproduce the observed spacer thickness and AOI dependences faithfully. The SERS intensity is expected to be strongly affected by the AOI on account for the fact that the hot spot formed in the space between the NP and the mirror is most efficiently excited with an electromagnetic field component that is normal to the surface of the mirror. Intriguingly we find that the SERS intensity maximizes at ∼60° and show that this is due to the coherent superposition of the incident and the reflected field components. (3) The observed SERS intensity is also shown to be very sensitive to the dielectric constant of the oxide spacer layer with the most intense signals obtained when using a low dielectric constant oxide layer (SiO2).

Materials Science

Physics

Collective excitations (including excitons, polarons, plasmons and other charge-density excitations)

Condensed matter: electronic structure, electrical, magnetic, and optical properties

Condensed matter: structure, mechanical and thermal properties

Cross-disciplinary physics: materials science; rheology

Dielectric thin films

Dielectrics, piezoelectrics, and ferroelectrics and their properties

Electronic structure and electrical properties of surfaces, interfaces, thin films and low-dimensional structures

Exact sciences and technology

Low-dimensional structures (superlattices, quantum well structures, multilayers): structure, and nonelectronic properties

Nanocrystalline materials

Nanoscale materials and structures: fabrication and characterization

Surface and interface electron states

Surfaces and interfaces; thin films and whiskers (structure and nonelectronic properties)

Details

Title: Subtitle: Plasmonic Properties of Gold Nanoparticles Separated from a Gold Mirror by an Ultrathin Oxide
Creators: Syed Mubeen - University of California, Santa Barbara
SHUNPING Zhang - Chinese Academy of Sciences
Namhoon Kim - University of California, Santa Barbara
Seungjoon Lee - University of California, Santa Barbara
Stephan Krämer - University of California, Santa Barbara
HONGXING XU - Chinese Academy of Sciences
Martin Moskovits - University of California, Santa Barbara
Resource Type: Journal article
Publication Details: Nano letters, Vol.12(4), pp.2088-2094
Publisher: American Chemical Society
DOI: 10.1021/nl300351j
PMID: 22414097
ISSN: 1530-6984
eISSN: 1530-6992
Language: English
Date published: 2012
Academic Unit: Civil and Environmental Engineering; Chemical and Biochemical Engineering
Record Identifier: 9984197203802771

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