Search results for "nanostructure"
showing 10 items of 792 documents
Discerning the Origins of the Amplitude Fluctuations in Dynamic Raman Nanospectroscopy
2012
International audience; We introduce a novel experimental and analytical method for discerning rare surface-enhanced Raman scattering (SERS) events observable at the nanoscale. We show that the kinetics of the Raman activity recorded on an isolated nanostructure is punctuated by intense and rare events of large amplitude and spectral variations. The fluctuations of thousands of SERS spectra were analyzed statistically in terms of power density functions, and the occurrence of the rare events was quantified by a wavenumber statistics. Our analysis enables one to extract valuable and unique spectroscopic signature of Raman variations usually hidden in time-average or space-average measurement…
Cluster Origin of Solvation Features of C-Nanostructures in Organic Solvents
2016
The existence of fullerenes, Single-Wall Carbon Nanocones (SWNCs), especially Nanohorns (SWNHs), Single-Wall Carbon Nanotube (SWNT) (CNT) (NT), NT-Fullerene Bud (NT-BUD), Nanographene (GR) and GR-Fullerene Bud (GR-BUD) in cluster form is discussed in organic solvents. Theories are developed based on columnlet, bundlet and droplet models describing size-distribution functions. The phenomena present a unified explanation in the columnlet model in which free energy of cluster-involved GR comes from its volume, proportional to number of molecules n in cluster. Columnlet model enables describing distribution function of GR stacks by size. From geometrical considerations, columnlet (GR/GR-BUD), b…
Thermal Effects of Water Intrusion in Hydrophobic Nanoporous Materials.
2009
Liquid water intrusion in hydrophobic nanoporous silicalite-1, a pure siliceous zeolite, in isothermal conditions under high pressure produces an endothermic effect. After intrusion, confined water in zeolite pores is in a different state from that of the liquid bulk water. Such forced intrusion also chemically modifies the material and tends to render it slightly more hydrophilic.
Coupling chemical reaction to electrospray: a novel preparation of gold nanostructures
2014
The simultaneous reduction of Au(III) to Au(0), synthesis of gold nanoparticles and their deposition onto boron-doped silicon target have been attained by the electrospray technique. In this way the overall process can be considered as a novel chemical/physical hybrid method which synergically exploits the merits of both approaches. Various experimental conditions have been explored to optimize the process: it has been found that, by applying a negative high voltage to the boron-doped silicon target and with the presence of the surfactant Bis(2-ethylhexyl)sulfosuccinate sodium salt in the solution, a quantitative transformation of Au(III) to Au(0) nanoparticles has been obtained. The deposi…
ETUDE ET RÉALISATION D'UN DETECTEUR (FILTRE) MULTISPECTRAL PAR DISPERSION NON DESTRUCTIVE SPECTRALE A TRAVERS DES FILMES A NONSTRUCTURE
2020
The development of multispectral imaging, holography and lithography techniques exploits the properties of diffracting arrays in a wide variety of photonic components. They are incorporated in laser diodes as distributed Bragg reflectors, in various integrated optical functions for wavelength division multiplexing or optical interconnections, or inscribed within the fibers themselves, leading to a wide variety of sensors for detection of chemical elements, measurement of temperatures, pressures, accelerations of acquisition and or restitution of multispectral images, etc. [Lee et al. 2007] [Pagnoux et al. 2005].Among these devices, the resonant networks arouse a great interest because they …
Surface Coordination of Multiple Ligands Endows N‐Heterocyclic Carbene‐Stabilized Gold Nanoclusters with High Robustness and Surface Reactivity
2020
Deciphering the molecular pictures of the multi-component and non-periodic organic-inorganic interlayer is a grand technical challenge. Here we show that the atomic arrangement of hybrid surface ligands on metal nanoparticles can be precisely quantified through comprehensive characterization of a novel gold cluster, Au 44 ( i Pr 2 -bimy) 9 (PA) 6 Br 8 , which features three types of ligands, namely, carbene (1,3-diisopropylbenzimidazolin-2-ylidene, i Pr 2 -bimy), alkynyl (phenylacetylide, PA), and halide (Br), respectively. The delicately balanced stereochemical effects and bonding capabilities of the three ligands give rise to peculiar geometrical and electronic structures. Remarkably, des…
Low-Temperature Miniemulsion-Based Routes for Synthesis of Metal Oxides.
2020
Abstract The use of miniemulsions containing chemical precursors in the disperse phase is a versatile method to produce nanoparticles and nanostructures of different chemical nature, including not only polymers, but also a variety of inorganic materials. This Minireview focuses on materials in which nanostructures of metal oxides are synthesized in processes that involve the miniemulsion technique in any of the steps. This includes in the first place those approaches in which the spaces provided by nanodroplets are directly used to confine precipitation reactions that lead eventually to oxides. On the other hand, miniemulsions can also be used to form functionalized polymer nanoparticles th…
Stability limits of elemental 2D metals in graphene pores
2019
Two-dimensional (2D) materials can be used as stabilizing templates for exotic nanostructures, including pore-stabilized, free-standing patches of elemental metal monolayers. Although these patches represent metal clusters under extreme conditions and are thus bound for investigations, they are poorly understood as their energetic stability trends and the most promising elements remain unknown. Here, using density-functional theory simulations and liquid drop model to explore the properties of 45 elemental metal candidates, we identify metals that enable the largest and most stable patches. Simulations show that pores can stabilize patches up to $\sim 8$ nm$^2$ areas and that the most promi…
Electromechanics of graphene spirals
2014
Among the most fascinating nanostructure morphologies are spirals, hybrids of somewhat obscure topology and dimensionality with technologically attractive properties. Here, we investigate mechanical and electromechanical properties of graphene spirals upon elongation by using density-functional tight-binding, continuum elasticity theory, and classical force field molecular dynamics. It turns out that electronic properties are governed by interlayer interactions as opposed to strain effects. The structural behavior is governed by van der Waals interaction: in its absence spirals unfold with equidistant layer spacings, ripple formation at spiral perimeter, and steadily increasing axial force;…
High-rate cycling performance of lead-acid batteries with nanostructured electrodes
2021
In this work we present lead-acid batteries with nanostructured electrodes cycled with different C-rate from 1C (1 hour to complete charge) up to 30C (120 seconds to complete charge) and imposing a very deep discharge. In comparison to the parameters usually used for commercial batteries, these are much more stressful conditions in terms of cut-off and charge/discharge rate.