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Synthèse, auto-assemblage et caractérisation d'architectures colloïdales hybrides plasmons-émetteurs

Abstract : This thesis proposes several approaches to control the structure of hybrid assemblies from element synthesis to self-organization and studies their emerging optical properties. In the first part we show that we can control the coupling in two ways. Either by functionalizing gold nanoparticles with a ligand able to recognize and immobilize the emitters or by creating a scaffolding biomolecule carrying fluorescent and plasmonic particle grafting sites. In the first case, a synthesis of gold prisms in the presence of artificial proteins, possibly biotinylated, covering their surface is carried out. The size and shape of the prisms determine the desired spectral properties of the plasmon resonances. Their high sensitivity to a variation of their dielectric environment (300 nm / RIU) allowed the detection of streptavidin on an individual prism. Alternatively, the engineering of a pair of artificial proteins whose strong mutual interaction triggers spontaneous precipitation. Transmission electron cryo-microscopy (cryo-TEM) and X-ray scattering characterization show the precise formation of tubular supercoils 5.8 nm in diameter and several microns in length. The amino acids of these proteins can be modified to graft different particles. The second part of this manuscript deals with a new synthesis, structural characterization, and photo-physical properties of Aun gold clusters with 4 = n = 25. These are made stable, in aqueous solutions, by functionalization with thiols. terminal function pegylates, including biotin. White fluorescence under broadband excitation and high quantum efficiency (up to 27%) make this mixture a promising emitter for hybrid structures. These Aun-biotin, but also biotinylated nanodiamonds, were attached to the protein gold prisms above. The proteins on the surface of the prisms make it possible to control locally and specifically the grafting of emitters at 5 nm from the gold surface. The last part of this thesis is devoted to the study of the optical properties of plasmonic structures alone then coupled to emitters. A comparison of hyperspectral images of dark-field scattering and cathodoluminescence in TEM, backed by a digital study combining Green's dyadic method and that of the finite elements, makes it possible to identify the bright and dark plasmons modes to which the photons emitted by fluorophores, depending on their position.
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Submitted on : Tuesday, March 30, 2021 - 10:10:09 AM
Last modification on : Wednesday, October 26, 2022 - 4:03:59 AM

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2020TOU30193a.pdf
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  • HAL Id : tel-03185063, version 1

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L. Moreaud. Synthèse, auto-assemblage et caractérisation d'architectures colloïdales hybrides plasmons-émetteurs. Autre [cond-mat.other]. Université Paul Sabatier - Toulouse III, 2020. Français. ⟨NNT : 2020TOU30193⟩. ⟨tel-03185063⟩

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