Optical properties of nanoporous gold foams

We fabricated and experimentally studied Au nano-foams and Al2O3 scaffolds filled with Au nanoparticles (NPs). We found that while the reflectance spectra of Au nano-foams depended very little on the 8-10 nm Al2O3 ALD coating, the spectra were highly sensitive to annealing, which increased the sizes...

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Bibliographic Details
Published inAIP advances Vol. 8; no. 9
Main Authors Asane, J. K., Qi, Z., Biener, M. M., Liberman, V., Noginov, M. A.
Format Journal Article
LanguageEnglish
Published United States American Institute of Physics (AIP) 04.09.2018
Subjects
dielectric properties
effective medium approximation
MATERIALS SCIENCE
metal oxides
nanomaterials
nanoparticles
optical properties
reflectometry
thin films
transition metals
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Summary:We fabricated and experimentally studied Au nano-foams and Al2O3 scaffolds filled with Au nanoparticles (NPs). We found that while the reflectance spectra of Au nano-foams depended very little on the 8-10 nm Al2O3 ALD coating, the spectra were highly sensitive to annealing, which increased the sizes of voids and ligaments from 50-100 nm to ~300 nm. The effective dielectric permittivities of the Au nano-foams and Al2O3 scaffolds with Au NPs were extremely high, ~50. At the same time, Au nano-foams covered with a dielectric (MgF2) featured bright structural colors, calling for the model, which extends beyond the effective medium approximation.
Bibliography:LLNL-JRNL-746772
US Army Research Office (ARO)
USDOE
National Science Foundation (NSF)
US Air Force Office of Scientific Research (AFOSR)
AC52-07NA27344; 1205457; 1646789; FA9550-14-1-0221; FA8721-05-C-0002; FA8702-15-D-0001; W911NF-14-1-0639
ISSN:2158-3226
2158-3226