engleski

Plasmonics of noble metal nanoparticles

A field with a high impact in nanoscience and nanotechnology today is plasmonics. The term plasmon refers to collective oscillations of conduction electrons in plasmonic materials, i.e. oscillations of charge density. Plasmonic effects are based on interaction processes between electromagnetic radiation and conduction electrons at metallic interfaces or in small metallic nanostructures, leading to an enhanced optical near field of sub-wavelength dimensions. Thus, it makes plasmonics a major part of the fascinating field of nanophotonics, which explores how electromagnetic fields can be confined within dimensions on the order of or smaller than the wavelength. In the focus of our research are nanoparticles of noble metals (silver, copper and gold) which, when illuminated by light, show unique optical properties due to the localized surface plasmon (LSP) resonance of free electrons. Besides detailed theoretical modelling of their plasmonic properties and interactions, we produce them in the form of metal island films (MIFs) which consist of metal nanoparticles deposited on a substrate upon evaporation in high vacuum. An overview of our research activities in this field over the last years is presented. Strong plasmonic absorption of noble MIFs at specific wavelengths depends on the particle size, shape, spatial distribution and dielectric environment, thus LSP properties of noble MIFs may be tailored by changing experimental parameters during sample preparation (amount of material, substrate temperature and deposition rate) or by changing dielectric environment around metal nanoparticles. Also, the LSP properties of noble MIFs can be tailored by post-deposition treatments (e.g. high-temperature annealing). Further tuning of the LSP resonance over a wide energy range can be obtained using bimetallic nanoparticles (e.g., gold-silver), either as core-shell or as alloyed structure. Due to this capacity of tailoring the optical properties, noble MIFs are interesting for various applications (e.g. novel approach to design of optical coatings). Finally the electric field assisted dissolution of metal nanoparticles (EFAD), owing to its simplicity and inexpensive technical requirements, represents an attractive possibility for production of low-cost plasmon-based two-dimensional and three-dimensional photonic structures.

surface plasmon resonance; noble metal nanoparticles

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