Magnetic and Electric Resonances in Particle-to-Film-Coupled Functional Nanostructures

• Published in: ACS applied materials & interfaces Vol. 10; no. 3; pp. 3133 - 3141
• Main Authors: Brasse, Yannic, Müller, Mareen B, Karg, Matthias, Kuttner, Christian, König, Tobias A. F, Fery, Andreas
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 24.01.2018
• Subjects: PNIPAM; plasmonic film coupling; gold nanoparticle; core/shell; gradient; magnetic and electric field enhancement
• ISSN: 1944-8244; 1944-8252
• DOI: 10.1021/acsami.7b16941

We investigate the plasmonic coupling of metallic nanoparticles with continuous metal films by studying the effect of the particle-to-film distance, cavity geometry, and particle size. To efficiently screen these parameters, we fabricated a particle-to-film-coupled functional nanostructure for which the particle size and distance vary. We use gold-core/poly­(N-isopropylacrylamide)-shell nanoparticles to self-assemble a monolayer of well-separated plasmonic particles, introduce a gradient in the nanoparticle size by an overgrowth process, and finally add a coupling metal film by evaporation. These assemblies are characterized using surface probing and optical methods to show localized magnetic and electric field enhancement. The results are in agreement with finite-difference time-domain modeling methods and calculations of the effective permeability and permittivity. Finally, we provide a proof of concept for dynamic tuning of the cavity size by swelling of the hydrogel layer. Thus, the tunability of the coupled resonance and the macroscopic self-assembly technique provides access to a cost-efficient library for magnetic and electric resonances.