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O: Fachverband Oberflächenphysik
O 43: Plasmonics and Nanooptics IV
O 43.8: Talk
Wednesday, March 13, 2013, 12:15–12:30, H31
Voltage clamped single gold nanoparticles as nanoscale pH-sensors — •Cynthia Vidal1, Martin Djiango1, Calin Hrelescu1, Thomas A. Klar1, Andrei I. Mardare2, and Achim Walter Hassel2 — 1Institute of Applied Physics, — 2Institute for Chemical Technology of Inorganic Materials, Johannes Kepler University, 4040 Linz, Austria
The surface chemistry of gold nanoparticles plays a crucial role when used in biodiagnostics, in surface enhanced Raman scattering and catalysis. The processes of double layer charging, increased damping of the plasmons due to adsorbates, and oxidation of single gold nanorods were recently investigated by optical dark field spectroscopy of voltage-clamped single gold nanoparticles [1,2]. In this work, the pH-dependence of the reversible formation/reduction of hydrous gold oxide layers on a single nanoparticle was investigated by combining electrochemistry with monitoring the plasmon resonance of single gold nanorods in a dark field microscope. Changing from an acidic environment to a more basic one, a shift of the hydrous oxide reduction point to lower potentials is observed. In combination with cyclic voltammetry results, the spectral shifts of the nanoparticle plasmon resonance can be correlated with these phenomena. The presented combination of electrochemistry and optical spectroscopy at a single nanoparticle level allows for the use of single gold nanoparticles as nanoelectrodes, providing a novel tool for electrochemistry and electro catalysis on the nanoscale. [1] Nano Lett. 12, 1247 (2012) [2] Nanoscale 4, 2339 (2012)