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Metallic nanoparticles present collective resonances of their electrons at optical frequencies (plasmon resonances). These resonances depend strongly on the composition, shape and near environment of the nanoparticles and are accompanied by strong light scattering and absorption.
Usually, light is controlled by redirecting the wave fronts of propagating radiation with lenses, mirrors, and diffractive elements. This type of manipulation relies on the wave nature of electromagnetic fields and is therefore not suitable to control fields on the subwavelength scale. Radio- and microwave technology on the other hand makes use of antennas to manipulate electromagnetic fields on the subwavelength scale and interfacing efficiently between propagating radiation and localized fields. In the first part of this talk I will present calculations and experimental results that demonstrate how the strong light scattering by metallic nanoparticles enables their use as resonant optical nano-antennas for single emitters [1,2]. The second part of the talk is based on the strong light absorption. Since almost all energy absorbed by the nanoparticles is converted into heat, they can be used as optically-driven nanoscopic sources of heat. I will present experiments that illustrate the use of single gold nanoparticles as optically controlled nano heat sources and how they are used to study locally phase transitions in phospholipid membranes [3]. Experiments like this one may contribute to obtain local thermodynamic information of complex systems, with nanometric resolution. Finally, I will introduce a new method that enables the immobilization of individual nanoparticles on precise positions of a substrate. The potential of this technique is demonstrated by printing single gold nanoparticles, one by one, with a precision of about 50 nm [4]. [1] T H Taminiau et al. Nature Photonics 2 (2008) 234-237. [2] T H Taminiau et al. Nano Letters 11 (2011) 1020-1024. [3] A S Urban et al. Nano Letters 9 (2009) 2903-2908. [4] A S Urban et al. Nano Letters 10 (2010) 4794-4798. |
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