Title: Quantitative measurement of the optical cross-sections of single nano-objects by correlative transmission and scattering micro-spectroscopy

Zilli A, Langbein WW, Borri P (2019). Quantitative measurement of the optical cross-sections of single nano-objects by correlative transmission and scattering micro-spectroscopy. Cardiff University. http://doi.org/10.17035/d.2018.0064868399

Access Rights: Data can be made freely available subject to attribution
Access Method: Click to email a request for this data to opendata@cardiff.ac.uk

Cardiff University Dataset Creators

Dataset Details
Publisher: Cardiff University
Date (year) of data becoming publicly available: 2019
Data format: .jpg, .tif, .png, .txt, .mph, m, .opj
Software Required: mph files are Comsol models. m files are Matlab scripts. opj files are Origin projects.
Estimated total storage size of dataset: Less than 100 megabytes
Number of Files In Dataset: 92
DOI: 10.17035/d.2018.0064868399


This dataset, provided as a single zip archive, contains the raw data of the paper: "Quantitative measurement of the optical cross-sections of single nano-objects by correlative transmission and scattering micro-spectroscopy", ACS Photonics 2019 (DOI: 10.1021/acsphotonics.9b00727). In this work we reported a method to quantify the magnitude of the optical absorption and scattering cross-section of individual nano-objects. Such quantitative analysis can be applied to data obtained either with single-particle micro-spectroscopy or with automated analysis of widefield images. The analysis requires the correlation of transmission images obtained under brightfield illumination and scattering images obtained under darkfield illumination. The cross-section quantitation relies on the calculation of the angular distribution of the power scattered by the nano-object to the far-field, and its dependence on the direction of incidence. In this work, this calculation is performed based on an analytical model of the scattering process in the electrostatic limit, so that it is appropriate to describe nano-objects which are small with respect to the wavelength of the incident light. In this work, we also discuss an accurate approach to simulating numerically the optical cross-sections of nano-objects. In particular, we reproduce the conditions of microscopy experiments, including the presence of the substrate, incoherent illumination with a large angular range of incidence on the sample, and the finite collection of the objective lens in the far-field. Comparison of the quantitative cross-section measurements with these accurate simulations can provide an estimate of unknown parameters of the system (e.g. a geometric dimension of the nano-object) by using them as fit parameters to match simulation and experiment. We call optical sizing such analysis procedure, whereby some geometrical parameter of a nano-object is assessed with purely optical measurements. We demonstrated this thorough optical characterization on three widely studies types of nanoparticles: Gold spheres of 60 nm diameter, gold rods of 28 nm width and 2.3 aspect ratio, and polystyrene spheres of 100 nm diameter.

This dataset, along with the methodology reported in the above cited paper and its Supporting information, includes all the necessary materials and instructions for other to check the accuracy of our measurement and implement the quantitative method with their own set-up. Specifically, we include:

  • All data represented in the figures of the article cited above or its Supporting information
  • Extensive structural characterization of the studied particles, including electron microscopy images of the metal particles and dynamic light scattering characterization of the polystyrene spheres
  • Darkfield scattering micrographs of the studied samples, to show the eyepiece impression and demonstrate the good particle correlation of the rod spectroscopy in different environments
  • Detailed characterization of the performance of our optical microscope, and in particular the transmission of the condenser lens as a function of the numerical aperture, and its chromatic and spherical aberrations
  • Matlab script implementing the analytical model of dipolar scattering presented in the paper, which provide the parameters required to retrieve the cross-section magnitude; exemplary results computed with these scripts to test their behaviour in the region of the parameter space relevant to typical experiments
  • Raw transmission and scattering spectra and quantitative cross-sections of the metallic particles, which can be used as templates for quantitative cross-section measurement using micro-spectroscopy (in conjunction with the parameters provided by the script above)
  • Cross-section magnitude of about 1000 polystyrene sphere measured with automated analysis of widefield images in three colour channels
  • The Comsol model files used to simulate the optical cross-sections of the three studied particle systems as a function of their geometrical parameters and material properties
  • Datasets of the permittivity of gold in the visible and near infrared wavelength ranges which have been used in the numerical simulations mentioned above; these include several published datasets and their analytical modification to increase the damping up to large values of the damping parameter g
  • Intermediate steps and final results of the optical sizing procedure described above applied to the three studied particle samples

The HTML document named "Data_Description" in the base folder of the archive contains a description of each item of the dataset and its path in the folder tree. It also includes two "Figure key" sections which allow to retrieve the data corresponding to a specific figure in the article cited above or its Supporting information.


Darkfield micro-spectroscopy, Nanoparticles, Nanoplasmonics, Optical cross-sections, Particle sizing, Rayleigh scattering, Single-particle microscopy, UV-Vis absorption spectra

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Last updated on 2019-19-12 at 14:32