Nanoplasmonic sensing of metal-halide complex formation and the electric double layer capacitor
Journal article, 2012

Many nanotechnological devices are based on implementing electrochemistry with plasmonic nanostructures, but these systems are challenging to understand. We present a detailed study of the influence of electrochemical potentials on plasmon resonances, in the absence of surface coatings and redox active molecules, by synchronized voltammetry and spectroscopy. The experiments are performed on gold nanodisks and nanohole arrays in thin gold films, which are fabricated by improved methods. New insights are provided by high resolution spectroscopy and variable scan rates. Furthermore, we introduce new analytical models in order to understand the spectral changes quantitatively. In contrast to most previous literature, we find that the plasmonic signal is caused almost entirely by the formation of ionic complexes on the metal surface, most likely gold chloride in this study. The refractometric sensing effect from the ions in the electric double layer can be fully neglected, and the charging of the metal gives a surprisingly small effect for these systems. Our conclusions are consistent for both localized nanoparticle plasmons and propagating surface plasmons. We consider the results in this work especially important in the context of combined electrochemical and optical sensors.

optical biosensors

selective detection

arrays

spectroscopy

surface-plasmon resonance

gold nanoparticles

sensors

impedance

label-free detection

protein microarrays

Author

Andreas Dahlin

Chalmers, Applied Physics, Bionanophotonics

Raphael Zahn

Swiss Federal Institute of Technology in Zürich (ETH)

J. Vörös

Swiss Federal Institute of Technology in Zürich (ETH)

Nanoscale

2040-3364 (ISSN)

Vol. 4 7 2339-2351

Subject Categories

Chemical Engineering

DOI

10.1039/c2nr11950a

More information

Latest update

3/19/2018