Optical response of heterogeneous polymer layers containing silver nanostructures.

Miriam Carlberg,Gérard Berginc,Olivier Margeat,Florent Pourcin,Jörg Ackermann,Judikaël Le Rouzo,Rose-Marie Sauvage,Ludovic Escoubas

doi:10.3762/bjnano.8.108

Abstract

This work is focused on the study of the optical properties of silver nanostructures embedded in a polymer host matrix. The introduction of silver nanostructures in polymer thin films is assumed to result in layers having adaptable optical properties. Thin film layers with inclusions of differently shaped nanoparticles, such as nanospheres and nanoprisms, and of different sizes, are optically characterized. The nanoparticles are produced by a simple chemical synthesis at room temperature in water. The plasmonic resonance peaks of the different colloidal solutions range from 390 to 1300 nm. The non-absorbing, transparent polymer matrix poly(vinylpyrrolidone) (PVP) was chosen because of its suitable optical and chemical properties. The optical studies of the layers include spectrophotometry and spectroscopic ellipsometry measurements, which provide information about the reflection, transmission, absorption of the material as well as the complex optical indices, n and k. Finite difference time domain simulations of nanoparticles in thin film layers allow the visualization of the nanoparticle interactions or the electric field enhancement on and around the nanoparticles to complete the optical characterization. A simple analysis method is proposed to obtain the complex refractive index of nanospheres and nanoprisms in a polymer matrix.

Highlights

Noble metal nanoparticles (NPs) are of considerable interest in various domains, ranging from chemistry to medicine and light filtering [1,2,3,4,5,6]
Finite difference time domain (FDTD) simulations show that the maximum electric field enhancement (Figure 1c) for p- and s-polarized light does not occur at the same wavelength
Spectroscopic ellipsometry measurement results were fit in the scope of an effective medium theory with the mathematical addition of the Cauchy law and a single Lorentz law

Summary

Introduction

Noble metal nanoparticles (NPs) are of considerable interest in various domains, ranging from chemistry to medicine and light filtering [1,2,3,4,5,6]. Silver NPs are especially challenging because of the possibility to control the phenomenon of light–matter interaction in the visible wavelength range. The optical properties of these metallic NPs are induced by localized surface plasmon resonances, which are size, shape, material and environment dependent [7]. At the localized surface plasmon resonance wavelengths, the conduction electrons of the NPs oscillate coherently, which induces an electric field enhancement.

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Conclusion