Regensburg 2013 – wissenschaftliches Programm

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MM: Fachverband Metall- und Materialphysik

MM 64: Nanomaterials - Miscellaneous

MM 64.1: Vortrag

Donnerstag, 14. März 2013, 17:15–17:30, H25

Plasmon resonances in Janus particles — •Sol Carretero-Palacios, Frank Jäckel, Theobald Lohmüller, and Jochen Feldmann — Photonics and Optoelectronics Group, Ludwig-Maximilians-Universität München, Department of Physics and Center for Nano-Science (CeNS), Amalienstr. 54, D-80799, München, Germany

Janus particles are particles whose surfaces have two or more different types of properties. Standard Janus particles used for optical manipulation consist of micro-silica core spheres half-coated with gold. The spherical asymmetry associated with Janus particles is the key point in many applications, including electrophoretic displays, nanoviscometers, and self-propelling micromachines. These systems possess a tunable plasmon resonance that can be controlled by changing the ratio of the core radius to the coating thickness.

We evaluate theoretically the extinction spectra of silica-gold Janus particles diluted in water, using a three-dimensional finite difference time domain (FDTD) method. We are able to tune the plasmon resonance from the near infrared to the optical regime by: i) half-coating the silica sphere with gold, but reducing the radius of the dielectric particle; ii) half-coating the silica particle with gold, but varying the ratio between radius and coating thickness; and iii) keeping both the radius and thickness fixed, but creating Dot-Janus particles, i.e., Janus particles which have a metallic coating covering < 50% of their surface area.