Quantitative morphometric analysis of single gold nanoparticles by optical extinction microscopy: material permittivity and surface damping effects

Payne, Lukas M., Masia, Francesco ORCID: https://orcid.org/0000-0003-4958-410X, Zilli, Attilio, Albrecht, Wiebke, Borri, Paola ORCID: https://orcid.org/0000-0002-7873-3314 and Langbein, Wolfgang ORCID: https://orcid.org/0000-0001-9786-1023 2021. Quantitative morphometric analysis of single gold nanoparticles by optical extinction microscopy: material permittivity and surface damping effects. Journal of Chemical Physics 154 , 044702. 10.1063/5.0031012

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Abstract

Quantifying the optical extinction cross section of a plasmonic nanoparticle has recently emerged as a powerful means to characterize the nanoparticle morphologically, i.e., to determine its size and shape with a precision comparable to electron microscopy while using a simple optical microscope. In this context, a critical piece of information to solve the inverse problem, namely, calculating the particle geometry from the measured cross section, is the material permittivity. For bulk gold, many datasets have been reported in the literature, raising the question of which one is more adequate to describe specific systems at the nanoscale. Another question is how the nanoparticle interface, not present in the bulk material, affects its permittivity. In this work, we have investigated the role of the material permittivities on the morphometric characterization of defect-free ultra-uniform gold nanospheres with diameters of 10 nm and 30 nm, following a quantitative analysis of the polarization- and spectrally-resolved extinction cross section on hundreds of individual nanoparticles. The measured cross sections were fitted using an ellipsoid model. By minimizing the fit error or the variation of the fitted dimensions with color channel selection, the material permittivity dataset and the surface damping parameter g best describing the nanoparticles are found to be the single crystal dataset by Olmon et al. [Phys. Rev. B 86, 235147 (2012)] and g ≈ 1, respectively. The resulting nanoparticle geometries are in good agreement with transmission electron microscopy of the same sample batches, including both 2D projection and tomography.

Item Type:	Article
Date Type:	Publication
Status:	Published
Schools:	Physics and Astronomy Biosciences
Publisher:	American Institute of Physics
ISSN:	0021-9606
Date of First Compliant Deposit:	18 January 2021
Date of Acceptance:	17 December 2020
Last Modified:	12 Nov 2024 23:00
URI:	https://orca.cardiff.ac.uk/id/eprint/137771

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