Centre d’Élaboration de Matériaux et d’Etudes Structurales


Accueil > Recherche > M3 : Matériaux Multi-échelles Multifonctionnels > Carbones nanostructurés > Development in Raman spectroscopy

Development in Raman spectroscopy

We use the various Raman setups of our laboratory and tailor the experiments to probe exactly the phenomenon to be studied.

With our cryostat, after adaptation, we are able to probe samples under inert atmosphere (1000 down to 78 K). Moreover, with polarizer and analyzer (linear or circular), we are able to determine the symmetry of the phonons. This is of high interest for perovskite where the strong electron-phonon is responsible of exceptional optical properties (as absorber or emitter) [Steele2018]. It is also possible to determine a rate of polarization for carbon fibers. With Tip Enhanced Raman Spectroscopy (TERS) experiment, a spatial resolution as small as 10 nm is reachable. We have used this resolution to probe carbon nanotubes [Puech2019]. As the wavelengths can be selected in a range going from UV to infra-red, we can observe effects dependent on the wavelength (inter-layer and intra-layer modes in twisted bi-layer graphene for example) [Eliel2018]. With our high-pressure diamond cell, we can probe materials in the pressure range of 0 to 20 GPa and thus monitor phase transitions and subtle phase equilibrium when the change in lattice parameter is very high as in Black Phosphorus [Kundu2020], allowing to better understand materials that we currently focus on such as diamanoids.
See : Eliel et al., Nature Comm. 9 (2018) 1 - Steele et al., ACS nano 12 (2018) 8081 - Puech et al., J. Carb. Res. 5 (2019) 69 - Kundu et al., Nano Lett. 20 (2020) 5929.

Intermediate field microscopy and finite size effect of focal spot
We take advantage of interference effects near surfaces to improve image resolution in optical microscopy. Using an optical scanning probe in collection mode, lateral standing waves can be recorded at variable distances from the surface. It turns out that intermediate field region outside the near field region, is distinctly different to both the near and far fields.

Schematic of incident, reflected beam and interference fringes near a surface and a point scatterer.
Right : cover of the book dedicated to this topic.

Imaging in the intermediate field enables a smooth transition between indirect (diffraction) and direct images. The image can be reconstructed from the recorded diffraction image by evaluating the Fresnel integral or through image convolution. We discovered though a collaboration with the Photonics Center at Boston University that the finite size of the focal spot leads to spectral shifts which need to be taken into account when recording Raman spectra from materials which vary at the nanometer scale. This was first discovered when performing spectral studies on a single carbon nanotube.
See : Bacsa et al., in Optics Near Surfaces and at the Nanometer Scale. Springer Briefs in Physics, Springer-Verlag (2020), Heidelberg, Germany (ISBN 978-3-030-58983-7)

NanoDESK (2017-2020) : developing web tools to help Companies with using nanocomponents in composites.

This is a European-funded action, Interreg type, to promote the investment in nanotechnology in the South of Europe, in a safe and sustainable way in the plastic sector, solving the current barriers by developing a set of tools to support companies with decision making. Outcomes include a compendium of web-based tools, providing applications to identify nanofillers (including carbon nanotubes and graphene) for targeted applications, advanced browsers to improve the access to related information or on-line characterization of toxicological profile and exposure potential to relevant nanomaterials.

Partners included : Faculdade de Ciencias, Universidade do Porto (FCUP), Portugal ; International Iberian Nanotechnology Laboratory (INL), Portugal ; Instituto Valenciano Seguridad y Salud Trabajo (Invassat), Spain ; Instituto Tecnológico del Embalaje, Transporte y Logística (ITENE), Spain ; ProtoQSAR, Spain, for the development and application of computational methods for the evaluation of physicochemical, biological and/or (eco)toxicological properties of chemicals, either of natural origin or synthesized ; Universitat Rovira i Virgili (URV), Spain, CEMES, through our Group, for characterization expertise.

CNT pour catalyse

Pile à combustible à base de polymère recouvert de composite nano-carbon
A travers un programme avec l’Inde (IITM, S. Ramaprabhu), nous voulons réduire l’utilisation de Pt et améliorer en même temps (...)

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Projet européen

La nanotechnologie pour inventer et développer des matériaux plastiques avec de nouvelles valeurs ajoutées : Projet Européen nanoDesk - INTERREG – SUDOE. Il a pour but de promouvoir les applications (...)

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Fabrication de membranes pour multi-observation : utilisation pour les nanotubes de carbone effondrés

La stratégie pour obtenir des nanotubes dogbones consiste à extraire les nanotubes (NTC) concentriques les uns des autres dans un échantillon de NTCs multiparois. Il est ensuite possible de les (...)

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