Quantitative Optical Microspectroscopy, Electron Microscopy, and Modelling of Individual Silver Nanocubes Reveals Surface Compositional Changes at the Nanoscale - data

This dataset, provided as a single zip archive, contains data related to the article: "Quantitative Optical Microspectroscopy, Electron Microscopy, and Modelling of Individual Silver Nanocubes Reveals Surface Compositional Changes at the Nanoscale", Nanoscale Advances 2020 (DOI: 10.1039/D0NA00059K). This work reports (i) a sample preparation methodology which allows correlating transmission electron microscopy (TEM) and optical micro-spectroscopy performed in different dielectric environments on a single nano-object; and (ii) an analysis method, applicable to a broad range of nano-systems, for analysing the spectroscopic data in order to accurately quantify the optical scattering and absorption cross section magnitude. (i) and (ii) are jointly demonstrated on a widely studied nanoparticle system: Colloidal silver cubes (75 nm side). By comparing the measured cross sections to numerical simulations based on the cube geometry determined via TEM for each cube, we assess on one hand the accuracy of the cross section measurements, and on the other hand how adequately the model describes the system. By systematically varying the main geometric and material parameters of the system, we find out that assuming a thin (~2 nm) tarnish layer has formed on the cube surface brings about a good agreement between simulation and experiment in both studied environments. In contrast, a layer of dielectric contaminant deposited on the surface – a hypothesis often invoked in literature – could not match the main resonance peak position and amplitude at the same time. While in this specific case tarnishing could be verified as well by other more direct chemically-specific techniques, our study aims at exemplifying what kind of knowledge can be gained by correlating a thorough optical characterization of the same nano-object in different environments to its structural characterization.

This dataset complements the article cited above and the associated supplementary information. It is meant to facilitate other researchers to thoroughly assess our work; and to help them performing quantitative cross section measurements on their own optical microscope with the methodology we propose. Specifically, we include in the data set:

• All data represented in the figures of the article and its Supporting information.
• High-resolution TEM images of individual cubes, with the extracted geometric parameters and the analysis of their correlation; and the analysis of the amount of tarnish seen in the TEM images and its correlation to the optical properties.
• Large area transmission and scattering optical micrographs, to show the overall appearance of the sample; assess the particle coverage of the surface and the stability of the binding upon a changing the immersion medium; and evaluate the damage to the supporting grid resulting from the high-energy electron beam used for TEM.
• The raw experimental spectroscopic data, and the cross-section spectra obtained via the quantitative analysis.
• The experimental characterization of the illumination in our set-up, which is required to carry out the quantitative analysis.
• The numerical models we used to compute the optical scattering and absorption spectra of the silver cubes.
• The scripts we used to automate the large parametric sweeps required to accurately simulate the cross sections under microscope illumination, and to perform the quantitative analysis.
• The simulated spectra as a function of multiple system parameters (geometry of the cube, tarnishing at its surface, modification of the local dielectric environment).

The base folder of the archive contains a HTML document called “Data_Description" which includes a brief description of each item of the dataset and its path in the folder tree. It also includes two "Figure key" section pointing to the data corresponding to each figure of the article and supplementary information.