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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 48: Nanoparticles and Composite Materials II

CPP 48.1: Vortrag

Freitag, 18. März 2011, 10:30–10:45, ZEU 114

Random nanoparticle patterns as unique optical labels for secure identification — •Alexander Schwemer¹, Ulrich Rührmair², and Ulrich Rant¹ — ¹Walter Schottky Institut, Technische Universität München, Am Coulombwall 3, 85748 Garching — ²Institut für Informatik VI, Technische Universität München, Boltzmannstraße 3, 85748 Garching

Complex macro-structures consisting of nanoscale objects hold great potential to be used as unique labels for secure identification, because the nanoscale features render it impossible to re-produce, i.e. forge, these patterns with nm accuracy on a large scale. Here, we present a straightforward and inexpensive approach to create and read-out optical labels based on ensembles of individual metallic nanoparticles. Gold nanorods, which exhibit two plasmonic resonances with distinct spectral and polarization features, are sparsely dispersed and immobilized on a solid substrate. Light scattered from the individual particles is imaged by a dark-field microscopy setup onto a consumer-electronics grade RGB CCD camera. By recording a set of polarization dependent images we are able to deduce a specific set of parameters for each particle which encompasses the particle's position (accuracy 150 nm), its spectral properties (color), and its angular orientation on the substrate (accuracy 0.2°). We describe the experimental realization and data-analysis routines to extract an extensive set of unique data in parallel from the nano-pattern and outline the implications of the introduced concept for future use in highly sensitive security applications for valuable items such as bank notes, passports or commercial goods.