Orateur
Description
Gold nanoparticles are a versatile tool for probing and monitoring their local environment. On the one hand, they exhibit optical extinction dominated by Localised Surface Plasmon Resonance (LSPR) whose spectral maxima and width are sensitive to their local environment. On the other hand, selective electrochemical reactions can be driven on electrodes with gold nanoparticles deposited on their surface, allowing, for example, the detection of heavy metal pollutants in water.
In this work, we have developed a setup combining Spatial Modulation Spectroscopy (SMS), which allows optical measurements on single nano-objects, and voltamperometric measurements. Synthesised Au bipyramids (100 nm in length) have been grafted by silanisation onto an ITO-coated glass substrate. This sample is used as the working electrode in a 0.1 M KNO3 electrolyte (counter electrode: Pt wire) in a 2 cm thick glass cell. The cell is mounted on an open vibrating piezoelectric stage and inserted into a home-built confocal microscope. Light from a collimated white lamp is focused onto the sample and collected in a spectrophotometer (wavelength range: 450-950 nm). Signals from the spectrophotometer are processed with a lock-in amplifier system to extract the extinction signal of individual nanoparticles. SEM images of the samples were also taken.
We performed potential cycling and recorded the optical response of Au bipyramids. The plasmonic responses to the stepwise applied potential show a redshift up to 40 nm and a decrease in intensity as the potential is increased from 0 to 1.4 V/Ag-AgCl (KCL sat.), which is consistent with the formation of a gold oxide layer on the surface of the nanoparticle. Analysis of the relationship between the potentials at which the gold oxidation reaction occurs and the associated change in the spectral characteristics of individual gold nanoparticles could enable the detection of deposited metallic contaminants.
| Do you submit an abstract for a talk or a poster? | poster |
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| If your abstract isn’t selected for a plenary talk, would you like to present it as a poster? | Yes |