Regensburg 2016 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 33: Photonics and Nanooptics I: Infrared Spectroscopy
O 33.5: Vortrag
Dienstag, 8. März 2016, 11:30–11:45, H4
Investigating diffractive coupling of fs-laser induced standing gold antennas for surface enhanced IR spectroscopy — •Ruslan Röhrich1, Tobias W. W. Mass1, Martin Reininghaus2, Reinhart Poprawe2, and Thomas Taubner1 — 1Institute of Physics (IA) RWTH Aachen — 2Fraunhofer Institute for Laser Technology ILT
IR resonant metallic nanoantennas induce enhanced and strongly localized electromagnetic fields. These nearfield enhancements are exploited in surface enhanced infrared absorption (SEIRA) spectroscopy to detect smallest quantities of molecules.
In this work micrometer-sized upright standing gold antennas are fabricated by irradiating a thin gold film with single femtosecond laserpulses [1]. Due to image charge formation in the surrounding gold film, the resonance wavelength of the antennas is proportional to 4 times the antenna length [2]. The hot spot of the structure is distant from the substrate which is beneficial for SEIRA applications compared to other geometries.
By arranging these antennas in arrays, coupling between multiple antennas occurs. Collective resonances can be used to achieve stronger nearfield enhancements [3]. FTIR measurements in grazing incidence geometry and simulations demonstrate that diffractive coupling plays a significant role in the spectral response of standing antenna arrays.
[1] Wortmann et al., J. Laser Appl. 24, 042017 (2012)
[2] Reininghaus et al., Opt. Express 21, 32176-32183 (2013)
[3] Adato et al., PNAS 106, 19227-19232 (2009)