Dresden 2014 – wissenschaftliches Programm

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DS: Fachverband Dünne Schichten

DS 9: Layer Properties: Electrical, Optical, and Mechanical Properties

DS 9.2: Hauptvortrag

Dienstag, 1. April 2014, 10:00–10:30, CHE 91

Polarized mid-infrared spectroscopy of split-ring resonators and metal nanoparticle-organic hybrids — •Thomas W.H. Oates, Dimitra Gkogkou, Timur Shaykhutdinov, Tolga Wagner, and Karsten Hinrichs — Leibniz-Institut für Analytische Wissenschaften - ISAS- e.V., Albert-Einstein Str. 9, 12489, Berlin, Germany

Metal nano-antennas are increasingly utilized to focus the electric far-field, with the goal of enhancing and manipulating interactions with organic resonators in the near-field. In the infrared spectral fingerprint region, the use of polarized infrared spectroscopy provides unique information concerning the 3D orientation of the resonant structures. We present the results of ellipsometry and polarized infrared microscopy investigations of an array of split-ring resonators (SRR) and metal nanoparticle (NP) films with adsorbed self-assembled monolayers. The SRRs show an extrinsic chiral response directly related to the combined symmetry of the metallic structures and the electric field of the incident radiation. Rigorous coupled wave analysis simulations give excellent agreement with the experimental results. The polarized reflection spectra of the metal NP-organic hybrids display surface-enhanced infrared absorption (SEIRA). Using a combinatorial fabrication method we produce an array of nanoparticle sizes, shapes and fill-factors on a single substrate. This allows us to precisely identify the optimal conditions for maximal SEIRA enhancement. The additional information provided by polarized spectroscopy allows us to discuss the origins of the SEIRA effect.