This README file was generated on [2025-07-23] by [Toulin Stéphane, Emmanuel O. Idowu, and Glenna L. Drisko].

Last update: [2025-07-23].

GENERAL INFORMATION

Data set title: Directional light scattering in Mie-resonant Si particles with ultra-thin Au shells
 
DOI: https://doi.org/10.5281/zenodo.16576971
 
Adresse de contact: stephane.toulin@icmcb.cnrs.fr / emmanuel.idowu@icmcb.cnrs.fr
 
METHODOLOGICAL INFORMATION 

- Dataset production context: In the present work, we present Au-decorated Si core-shell (Si@Au) particles, which show enhanced forward scattering compared to Mie-resonant Si particles alone. TEM images show the synthesized Si particles with size dispersity and the Au-decorated Si particles. The UV-Vis-NIR spectra and EDX spectroscopy further confirm the synthesis of Si@Au particles. The Si core sizes are between 100 – 200 nm, while the Au particles with ∼4 nm diameter form the shell. Electron energy-loss spectroscopy (EELS) mapping and optical single-particle backward-scattering spectroscopy confirm the resonant behavior of the core-shell particles. These observations were supported by T-matrix simulations and Mie-theory calculations of the scattering spectra, which show that Si and Si@Au particles demonstrate a dampened magnetic dipole resonance for smaller sizes (100 – 130 nm) and an enhanced magnetic dipole resonance for larger Si particle sizes (150 – 200 nm).

- Data description: This dataset consists of 12 OPJ files from figures 1, 2, 3, 4, and 5. Also, the supplementary dataset of figure S1, 2, 4, 6, 7, 8, 9, and 10 from the article.

OPJ Data of Figure 1. UV-vis-NIR extinction spectra of the Au-decorated Si particles with single coating (red), double coating (blue), and bare Si particles (black). Elemental mapping images obtained from particles.
- Description of sources and methods used to collect and generate data: UV-vis-NIR extinction spectra were recorded using a Shimadzu UV-3600 UV-vis-NIR extinction spectrometer. For elemental mapping of the Si@Au NPs, a ThermoFisher (FEI) Talos F200S G2 apparatus operating at 200 kV was used. Images were acquired using the software VELOX (Version 2.13.1.1138-af4e0daa7d).

- Methods for processing the data: Data treated with ImageJ and OriginPro 2018 SR1b.9.5.1.195.

OPJ Data of Figure 2 & S6. The samples were prepared by drop drying onto a lacey carbon grid. Electron energy loss spectroscopy (EELS) spectra for single particles of ∼ 140 and 180 nm diameter were taken from areas with particles unsupported by lacy carbon grid, and the corresponding High-angle annular darkfield Scanning TEM images, and EELS intensity maps.
- Description of sources and methods used to collect and generate data: STEM-EELS spectroscopy and mapping were performed with a monochromated NION HERMES-200S microscope fitted with a NION-IRIS spectrometer and a CMOS camera. The acceleration voltage was at 60 keV with a condenser semi-angle at 10 mrad and a typical energy resolution around 15 meV. All EELS spectrum images were aligned by the maximum of the zero-loss peak (ZLP) in each spectrum. 
- Methods for processing the data: Data treated with Gatan DigitalMicrograph (Version 3.60.4441.0).

OPJ Data of Figure 3. The single particle scattering spectra of the Si particles with the corresponding FE-SEM and darkfield optical images. T-matrix–simulated scattering spectra for bare Si and single coated Si@Au using Au particles of 4 nm diameter and 50 % surface coverage. 
- Description of sources and methods used to collect and generate data: Scattering spectra were measured with a commercial dark-field scattering microscope from Zeiss (Axio Imager Z2). The spectra were collected by a spectrometer (Ocean Optics QE65000) coupled with an optical fiber that has a 50 μm core size and a collection zone with a diameter of 3 μm on the glass substrate. Dark-field scattering images were captured using a color digital camera (Zeiss). The light source was a halogen lamp (Halogen 4100 K, Philips) with a broadband spectrum in the visible and infrared. The light illumination and the collection were carried out by a 50 × objective. Field-emission scanning electron microscope (FE-SEM) was performed using a FEG system (Hitachi SU 8030 N) with an acceleration voltage of 5−10 kV to characterize the morphology of the particles.
- Methods for processing the data: Data treated with ImageJ and OriginPro 2018 SR1b.9.5.1.195.

OPJ Data of Figure 4. Mie-theory (Si particles) and T-matrix (Si@Au) simulated scattering spectra of particles with different sizes for the forward, backward, and forward-to-backward scattering cross-sections.
- Description of sources and methods used to collect and generate data: The optical scattering spectra of the decorated spheres were simulated using the T-matrix method and implemented using the SMUTHI Python toolkit.
- Methods for processing the data: Data treated with OriginPro 2018 SR1b.9.5.1.195.

OPJ Data of Figure 5. T-matrix simulated scattering spectra for Si@Au particle with a 186 nm diameter Si core. Au particle shell ranging in thickness between 0 and 30 nm with a surface coverage of 50 %. A Mie-theory calculation for a bare Si and continuous Au shell between 0 and 30 nm in thickness.
- Description of sources and methods used to collect and generate data: Optical spectra for homogeneous spherical and continuous shell particles were calculated using Mie theory implemented using the PyMieScatt Python package.
- Methods for processing the data: Data treated with OriginPro 2018 SR1b.9.5.1.195.

OPJ Data of Figure S4. T-matrix simulated optical scattering cross-sections of hollow 186 nm shells comprised of a single layer of 5 nm Au particles with increasing density (10 – 60%). 
- Description of sources and methods used to collect and generate data: The optical scattering spectra of the decorated spheres were simulated using the T-matrix method and implemented using the SMUTHI Python toolkit.
- Methods for processing the data: Data treated with OriginPro 2018 SR1b.9.5.1.195.

OPJ Data of Figure S7. Peak of scattering wavelength of the ED and MD resonances of the single coating Au-decorated Si particles as a function of the silicon core diameter. The experimental data are linearly fitted (solid lines) for the ED and MD resonances. The core diameter ranges between 100 and 200 nm. 
- Description of sources and methods used to collect and generate data: As described in Figure 3.
- Methods for processing the data: Data treated with OriginPro 2018 SR1b.9.5.1.195.
OPJ Data of Figure S8. Single particle scattering spectroscopy of different diameters (105 – 200 nm) single coating Au-decorated Si particles with the corresponding darkfield optical images, and FE-SEM.
- Description of sources and methods used to collect and generate data: As described in Figure 3.
- Methods for processing the data: Data treated with OriginPro 2018 SR1b.9.5.1.195.

OPJ Data of Figure S9. Simulated optical scattering spectra for 152 nm silicon core decorated with different surface coverage of 4 nm diameter Au particles. Scattering wavelength (b) and intensity (c) as a function of the percentage surface coverage of Au nanoparticles.
- Description of sources and methods used to collect and generate data: As described in Figures 4 and 5.
- Methods for processing the data: Data treated with OriginPro 2018 SR1b.9.5.1.195.

OPJ Data of Figure S10. The single particle scattering spectra of the double-coated Si@Au Si particles with the corresponding FE-SEM and darkfield optical images.
- Description of sources and methods used to collect and generate data: As described in Figure 3.
- Methods for processing the data: Data treated with ImageJ and OriginPro 2018 SR1b.9.5.1.195.
