Tunable SERS Platforms from Small Nanoparticle 3D Superlattices: A Comparison between Gold, Silver, and Copper

Chapus, Lionel; Aubertin, Pierre; Joiret, S.; Lucas, Ivan T.; Maisonhaute, Emmanuel; Courty, Alexa

doi:10.1002/cphc.201700601

Cited by 15 publications

(17 citation statements)

References 45 publications

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“…Furthermore, micrometer-scale well-faceted 3D superlattices of ordered Au@Ag NPs were obtained and imaged by HR-SEM. The high quality of the NPs, whether in size control, chemical composition or crystallinity makes it possible to envisage these 3D superlattices as new SERS platforms with tunable optical properties [32,57,58]. The modulations in size and crystallinity of the core-shell Au@Ag NPs will promote their application in catalysis, where these parameters are known to play a fundamental role [13,30,31].…”

Section: Resultsmentioning

confidence: 99%

Versatile and robust synthesis process for the fine control of the chemical composition and core-crystallinity of spherical core–shell Au@Ag nanoparticles

et al. 2020

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Au nanoparticles (NPs) characterized by distinct surface chemistry (including dodecanethiol or oleylamine as capping agent), different sizes (~5 and ~10 nm) and crystallinities (polycrystalline or single crystalline), were chosen as seeds to demonstrate the versatility and robustness of our two-step core-shell Au@Ag NP synthesis process. The central component of this strategy is to solubilize the shell precursor (AgNO 3) in oleylamine and to induce the growth of the shell on selected seeds under heating. The shell thickness is thus controlled by the temperature, the annealing time, the [shell precursor] / [seed] concentration ratio, seed size and crystallinity. The shell thickness is thus shown to increase with the reactant concentration and to grow faster on polycrystalline seeds. The crystalline structure and chemical composition were characterized by HRTEM, STEM-HAADF, EELS and Raman spectroscopy. The plasmonic response of Au@Ag core-shell NPs as a function of core size and shell thickness was assessed by spectrophotometry and simulated by calculations based on the discrete dipole approximation (DDA) method. Finally, the nearly monodisperse coreshell Au@Ag NPs were shown to form micrometer-scale facetted 3D fcc-ordered superlattices (SLs) after solvent evaporation and deposition on a solid substrate. These SLs are promising candidates for applications as a tunable surface-enhanced Raman scattering (SERS) platform.

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Section: Resultsmentioning

confidence: 99%

Versatile and robust synthesis process for the fine control of the chemical composition and core-crystallinity of spherical core–shell Au@Ag nanoparticles

et al. 2020

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“…Both these conditions (structural and functional) are met by gold and silver nanoparticles (Au and Ag NPs) of few nanometer diameter (size range 3–6 nm). Such NPs do not exhibit as strong plasmonic properties as larger ones [ 27 , 63 , 64 ], however sub-10 nm Ag NPs are interesting in the context of their prospective applications in surface enhanced Raman spectroscopy [ 65 , 66 , 67 ] and for metamaterials preparation [ 68 ].…”

Section: Resultsmentioning

confidence: 99%

Modifying Thermal Switchability of Liquid Crystalline Nanoparticles by Alkyl Ligands Variation

et al. 2018

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By coating plasmonic nanoparticles (NPs) with thermally responsive liquid crystals (LCs) it is possible to prepare reversibly reconfigurable plasmonic nanomaterials with prospective applications in optoelectronic devices. However, simple and versatile methods to precisely tailor properties of liquid-crystalline nanoparticles (LC NPs) are still required. Here, we report a new method for tuning structural properties of assemblies of nanoparticles grafted with a mixture of promesogenic and alkyl thiols, by varying design of the latter. As a model system, we used Ag and Au nanoparticles that were coated with three-ring promesogenic molecules and dodecanethiol ligand. These LC NPs self-assemble into switchable lamellar (Ag NPs) or tetragonal (Au NPs) aggregates, as determined with small angle X-ray diffraction and transmission electron microscopy. Reconfigurable assemblies of Au NPs with different unit cell symmetry (orthorombic) are formed if hexadecanethiol and 1H,1H,2H,2H-perfluorodecanethiol were used in the place of dodecanethiol; in the case of Ag NPs the use of 11-hydroxyundecanethiol promotes formation of a lamellar structure as in the reference system, although with substantially broader range of thermal stability (140 vs. 90 °C). Our results underline the importance of alkyl ligand functionalities in determining structural properties of liquid-crystalline nanoparticles, and, more generally, broaden the scope of synthetic tools available for tailoring properties of reversibly reconfigurable plasmonic nanomaterials.

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“…High Raman enhancement occurs when molecules are close to highly polarizable objects, as metallic NPs, due to the intense localized electric fields produced by the LSPR for resonant incident energies [ 6 ]. The optical properties of metal nanoparticles depend on size, shape and composition of the NPs, consequently, there is an intense activity on the optimization of these parameters [ 7 – 10 ]. Indeed, the aspect ratio of metal nanorods allows controlling the resonance wavelengths and reaching the infrared range which is useful for different therapies [ 11 ].…”

Section: Introductionmentioning

confidence: 99%

Raman amplification in the ultra-small limit of Ag nanoparticles on SiO2 and graphene: Size and inter-particle distance effects

et al. 2020

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Size, shape and hot spots are crucial to optimize Raman amplification from metallic nanoparticle (NPs). The amplification from radius = 1.8 ± 0.4 nm ultra-small silver NPs was explored. Increasing NP density redshifts and widens their plasmon that, according to simulations for NPs arrays, is originated by the reduction of the interparticle distance, d, becoming remarkable for d ≤ R. Inter-particle interaction red-shifts (N130 nm) and widens (N90 nm) the standard plasmon of non-interacting spherical particles. Graphene partly delocalizes the carriers enhancing the NIR spectral weight. Raman amplification of graphene phonons is moderate and depends smoothly on d while that of Rhodamine 6G (R6G) varies almost exponentially due to their location at hotspots that depend strongly on d. The experimental correlation between amplification and plasmon position is well reproduced by simulations. The amplification originated by the ultra-small NPs is compared to that of larger particles, granular silver films with 7 < R < 15 nm grains, with similar extinction values. The amplification is found to be larger for the 1.8nm NPs due to the higher surface/volume ration that allows higher density of hot spots. It is demonstrated that Raman amplification can be efficiently increased by depositing low density layers of ultra-small NPs on top of granular films.

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Tunable SERS Platforms from Small Nanoparticle 3D Superlattices: A Comparison between Gold, Silver, and Copper

Cited by 15 publications

References 45 publications

Versatile and robust synthesis process for the fine control of the chemical composition and core-crystallinity of spherical core–shell Au@Ag nanoparticles

Versatile and robust synthesis process for the fine control of the chemical composition and core-crystallinity of spherical core–shell Au@Ag nanoparticles

Modifying Thermal Switchability of Liquid Crystalline Nanoparticles by Alkyl Ligands Variation

Raman amplification in the ultra-small limit of Ag nanoparticles on SiO2 and graphene: Size and inter-particle distance effects

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