Articoli di riviste: "Single metallic nanoparticles"

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Ngo, Minh Quang. "Localized Surface Plasmon Resonances with Spherical Metallic Nanoparticles". Communications in Physics 28, n. 2 (17 luglio 2018): 115. http://dx.doi.org/10.15625/0868-3166/28/2/11037.

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In this work we review in part of our recent theoretical study on the electrical intensity enhancement in the dielectric medium surrounding metallic nanoparticles due to the effect of their localized surface plasmon resonance (LSPR). The known results in the case of a simple metallic spherical nanoparticle are presented and then extend them to the general case of complex network of the identical spherical metallic nanoparticles. For illustration, several typical lattices of identical spherical metallic nanoparticles will be treated. The findings of electrical intensity enhancements and plasmonic resonance wavelengths of the single and the network of the metallic nanoparticles are obtained based on the analytical expressions. The theoretical results were compared and shown the good agreement with simulation results. The simulation of the LSPRs and the electrical intensity enhancements was performed using the boundary element method.

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Compostella, Federica, Olimpia Pitirollo, Alessandro Silvestri e Laura Polito. "Glyco-gold nanoparticles: synthesis and applications". Beilstein Journal of Organic Chemistry 13 (24 maggio 2017): 1008–21. http://dx.doi.org/10.3762/bjoc.13.100.

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Glyco-gold nanoparticles combine in a single entity the peculiar properties of gold nanoparticles with the biological activity of carbohydrates. The result is an exciting nanosystem, able to mimic the natural multivalent presentation of saccharide moieties and to exploit the peculiar optical properties of the metallic core. In this review, we present recent advances on glyco-gold nanoparticle applications in different biological fields, highlighting the key parameters which inspire the glyco nanoparticle design.

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Hohenester, U., e A. Trugler. "Interaction of Single Molecules With Metallic Nanoparticles". IEEE Journal of Selected Topics in Quantum Electronics 14, n. 6 (2008): 1430–40. http://dx.doi.org/10.1109/jstqe.2008.2007918.

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Klar, T., M. Perner, S. Grosse, G. von Plessen, W. Spirkl e J. Feldmann. "Surface-Plasmon Resonances in Single Metallic Nanoparticles". Physical Review Letters 80, n. 19 (11 maggio 1998): 4249–52. http://dx.doi.org/10.1103/physrevlett.80.4249.

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Ramos Uña, Rafael, Braulio García Cámara e Ángela I. Barreda. "An Evaluation of Moderate-Refractive-Index Nanoantennas for Enhancing the Photoluminescence Signal of Quantum Dots". Nanomaterials 14, n. 22 (14 novembre 2024): 1822. http://dx.doi.org/10.3390/nano14221822.

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The use of nanostructures to enhance the emission of single-photon sources has attracted some attention in the last decade due to the development of quantum technologies. In particular, the use of metallic and high-refractive-index dielectric materials has been proposed. However, the utility of moderate-refractive-index dielectric nanostructures to achieve more efficient single-photon sources remains unexplored. Here, a systematic comparison of various metallic, high-refractive-index and moderate-refractive-index dielectric nanostructures was performed to optimize the excitation and emission of a CdSe/ZnS single quantum dot in the visible spectral region. Several geometries were evaluated in terms of electric field enhancement and Purcell factor, considering the combination of metallic, high-refractive-index and moderate-refractive-index dielectric materials conforming to homogeneous and hybrid nanoparticle dimers. Our results demonstrate that moderate-refractive-index dielectric nanoparticles can enhance the photoluminescence signal of quantum emitters due to their broader electric and magnetic dipolar resonances compared to high-refractive-index dielectric nanoparticles. However, hybrid combinations of metallic and high-refractive-index dielectric nanostructures offer the largest intensity enhancement and Purcell factors at the excitation and emission wavelengths of the quantum emitter, respectively. The results of this work may find applications in the development of single-photon sources.

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Levratovsky, Y., e E. Gross. "High spatial resolution mapping of chemically-active self-assembled N-heterocyclic carbenes on Pt nanoparticles". Faraday Discussions 188 (2016): 345–53. http://dx.doi.org/10.1039/c5fd00194c.

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The properties of many functional materials critically depend on the spatial distribution of surface active sites. In the case of solid catalysts, the geometric and electronic properties of different surface sites will directly impact their catalytic properties. However, the detection of catalytic sites at the single nanoparticle level cannot be easily achieved and most spectroscopic measurements are performed with ensemble-based measurements in which the reactivity is averaged over millions of nanoparticles. It is hereby demonstrated that chemically-functionalized N-heterocyclic carbene molecules can be attached to the surfaces of Pt nanoparticles and utilized as a model system for studying catalytic reactions on single metallic nanoparticles. The formation of a carbene self-assembled layer on the surface of a Pt nanoparticle and its stability under oxidizing conditions were investigated. IR nanospectroscopy measurements detected the chemical properties of surface-anchored molecules on single nanoparticles. A direct correlation was identified between IR nanospectroscopy measurements and macroscopic ATR-IR measurements. These results demonstrate that high spatial resolution mapping of the catalytic reactivity on single nanoparticles can be achieved with this approach.

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Jahr, Norbert, Mamuna Anwar, Ondrej Stranik, Nicole Hädrich, Nadine Vogler, Andrea Csaki, Jürgen Popp e Wolfgang Fritzsche. "Spectroscopy on Single Metallic Nanoparticles Using Subwavelength Apertures". Journal of Physical Chemistry C 117, n. 15 (4 aprile 2013): 7751–56. http://dx.doi.org/10.1021/jp311135g.

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Yedoti, Venkateswarlu, e N. Supraja. "A Review on Algal Mediated Synthesized Metallic Nanoparticles: An Eco-Friendly Approach for Sustainable Nanotechnology". Current Journal of Applied Science and Technology 43, n. 6 (3 maggio 2024): 1–10. http://dx.doi.org/10.9734/cjast/2024/v43i64381.

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The field of nanotechnology has witnessed a paradigm shift in recent years, with an increasing emphasis on eco-friendly and sustainable synthesis methods for metallic nanoparticles. Algal-mediated synthesis, an emerging and promising technique, harnesses the bioactive compounds present in algae for the green synthesis of metallic nanoparticles. This process not only offers a sustainable alternative to conventional chemical methods but also holds the potential to revolutionize various industries, including medicine, energy, and environmental remediation. Microalgae, forming a substantial part of the planet’s biodiversity, are usually single-celled colony-forming or filamentous photosynthetic microorganisms, including several legal divisions like Chlorophyta, Charophyta, and Bacillariophyta. Whole cells of Plectonema boryanum (filamentous cyanobacteria) proved efficient in promoting the production of Au, Ag, and Pt nanoparticles. The cyanobacterial strains of Anabaena flos-aquae and Calothrix pulvinate were used to implement the biosynthesis of Au, Ag, and Pt nanoparticles. This abstract provides an overview of the key aspects of algal-mediated metallic nanoparticle synthesis. Algae, as a versatile source of bioactive compounds, serve as both reducing and stabilizing agents in the nanoparticle formation process. Various types of algae, including microalgae and macroalgae, have been explored for this purpose, each with distinct biochemical profiles that contribute to the synthesis process.

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Doan-Nguyen, Vicky, Simon Kimber, Diego Pontoni, Danielle Reifsnyder, Benjamin Diroll, Xiaohao Yang, Marcel Miglierini, Christopher Murray e Simon Billinge. "Size-dependent non-space filling atomic packing in metallic nanoparticles". Acta Crystallographica Section A Foundations and Advances 70, a1 (5 agosto 2014): C867. http://dx.doi.org/10.1107/s2053273314091323.

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Ni-Pd nanoparticles synthesized for CO catalysis are characterized by transmission electron microscopy and total X-ray scattering. The sizes of these nanoparticles can be tuned to size with great control over the monodispersity of the samples. The pair distribution functions of the reveal a local ordering within the highly disordered atomic structure within the nanoparticles. The PDFs show a size-dependent deviation from typical bulk face centered cubic (fcc) structure for these materials. The long-range isotropic disorder within these non-fcc nanoparticles can be fitted using an exponentially damped single-mode sine wave. Below a diameter of 5 nm, the Ni-Pd nanoparticles exhibit local ordering of atoms as found in typical icosahedral clusters. The transition from fcc to non-space filling atomic packing of icosahedral clusters in a nanoparticle is modeled to show the structural origin of the observed PDFs. Understanding this type of disorder can give insight into structure-property relations for applications in heterogeneous catalysis.

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Raza, Qadeer, M. Zubair Akbar Qureshi, Bagh Ali, Ahmed Kadhim Hussein, Behzad Ali Khan, Nehad Ali Shah e Wajaree Weera. "Morphology of Hybrid MHD Nanofluid Flow through Orthogonal Coaxial Porous Disks". Mathematics 10, n. 18 (9 settembre 2022): 3280. http://dx.doi.org/10.3390/math10183280.

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In this article, we study the novel features of morphological effects for hybrid nanofluid flow subject to expanding/contracting geometry. The nanoparticles are incorporated due to their extraordinary thermal conductivity and innovative work for hybrid nanofluids, which are assembled of aluminum oxides, Al2O3 metallic oxides, and metallic copper Cu. Cu nanoparticles demonstrate very strong catalytic activity, while Al2O3 nanoparticles perform well as an electrical insulator. The governing partial differential equations of the elaborated model are transformed into a system of nonlinear ordinary differential equations with the use of similarity variables, and these equations are numerically solved through a shooting technique based on the Runge–Kutta method. We develop a hybrid correlation for thermophysical properties based on a single-phase approach. A favorable comparison between shape and size factors for metallic and metallic-oxide nanoparticles is discussed via tables and figures. Moreover, the effect of embedding flow factors on concentration, velocity, and temperature is shaped in line with parametric studies, such as the permeable Reynolds number, nanoparticle volume fractions, and expansion/contraction parameters. The fluid velocity, temperature, and concentration are demonstrated in the presence of hybrid nanoparticles and are discussed in detail, while physical parameters such as the shear stress, flow of heat, and mass transfer at the lower and upper disks are demonstrated in a table. The hybrid nanoparticles show significant results as compared to the nanofluids. If we increase the nanoparticle volume fraction, this increases the thermal performance for an injection/suction case as well. The above collaborative research provides a strong foundation in the field of biomedical equipment and for the development of nanotechnology-oriented computers.

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Payne, Lukas, George Zoriniants, Francesco Masia, Kenton P. Arkill, Paul Verkade, Darren Rowles, Wolfgang Langbein e Paola Borri. "Optical micro-spectroscopy of single metallic nanoparticles: quantitative extinction and transient resonant four-wave mixing". Faraday Discussions 184 (2015): 305–20. http://dx.doi.org/10.1039/c5fd00079c.

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We report a wide-field imaging method to rapidly and quantitatively measure the optical extinction cross-section σ_ext (also polarisation resolved) of a large number of individual gold nanoparticles, for statistically-relevant single particle analysis. We demonstrate a sensitivity of 5 nm² in σ_ext, enabling detection of single 5 nm gold nanoparticles with total acquisition times in the 1 min range. Moreover, we have developed an analytical model of the polarisation resolved σ_ext, which enabled us to extract geometrical particle aspect ratios from the measured σ_ext. Using this method, we have characterized a large number of nominally-spherical gold nanoparticles in the 10–100 nm size range. Furthermore, the method provided measurements of in-house fabricated nanoparticle conjugates, allowing distinction of individual dimers from single particles and larger aggregates. The same particle conjugates were investigated correlatively by phase-resolved transient resonant four-wave mixing micro-spectroscopy. A direct comparison of the phase-resolved response between single gold nanoparticles and dimers highlighted the promise of the four-wave mixing technique for sensing applications with dimers as plasmon rulers.

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Zampardi, Giorgia, e Richard G. Compton. "Fast electrodeposition of zinc onto single zinc nanoparticles". Journal of Solid State Electrochemistry 24, n. 11-12 (14 marzo 2020): 2695–702. http://dx.doi.org/10.1007/s10008-020-04539-9.

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Abstract The zinc deposition reaction onto metallic zinc has been investigated at the single particle level through the electrode-particle collision method in neutral solutions, and in respect of its dependence on the applied potential and the ionic strength of a sulphate-containing solution. Depending on the concentration of sulphate ions in solution, different amounts of metallic zinc were deposited on the single Zn nanoparticles. Specifically, insights into the electron transfer kinetics at the single particles were obtained, indicating an electrically early reactant-like transition state, which is consistent with the rate-determining partial de-hydration/de-complexation process. Such information on the reaction kinetics at the nanoscale is of vital importance for the development of more efficient and long-lasting nanostructured Zn-based negative electrodes for Zn-ion battery applications.

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Gayduchenko, Igor, Georgy Fedorov, Ramil Ibragimov, Tatiana Stepanova, Arsen Gazaliev, Nikolay Vysochanskiy, Yuri Bobrov, Anton Malovichko, Ilya Sosnin e Ivan Bobrinetskiy. "Synthesis of single-walled carbon nanotube networks using monodisperse metallic nanocatalysts encapsulated in reverse micelles". Chemical Industry 70, n. 1 (2016): 1–8. http://dx.doi.org/10.2298/hemind140910005g.

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We report on a method of synthesis of single-walled carbon nanotubes percolated networks on silicon dioxide substrates using monodisperse Co and Ni catalyst. The catalytic nanoparticles were obtained by modified method of reverse micelles of bis-(2-ethylhexyl) sulfosuccinate sodium in isooctane solution that provides the nanoparticle size control in range of 1 to 5 nm. The metallic nanoparticles of Ni and Co were characterized using transmission electron microscopy (TEM) and atomic-force microscopy (AFM). Carbon nanotubes were synthesized by chemical vapor deposition of CH4/H2 composition at temperature 1000 ?? on catalysts pre-deposited on silicon dioxide substrate. Before temperature treatment during the carbon nanotube synthesis most of the catalyst material agglomerates due to magnetic forces while during the nanotube growth disintegrates into the separate nanoparticles with narrow diameter distribution. The formed nanotube networks were characterized using AFM, scanning electron microscopy (SEM) and Raman spectroscopy. We find that the nanotubes are mainly single-walled carbon nanotubes with high structural perfection up to 200 ?m long with diameters from 1.3 to 1.7 nm consistent with catalyst nanoparticles diameter distribution and independent of its material.

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Ferrando, Riccardo. "Mass Transport in Nanoalloys Studied by Atomistic Models". Diffusion Foundations 12 (settembre 2017): 23–37. http://dx.doi.org/10.4028/www.scientific.net/df.12.23.

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The diffusion of atoms in nanoparticles can be studied computationally by Molecular Dynamics simulations, a simulation method which allow to follow the actual trajectories of the diffusing atoms. Here we focus on the simulation of diffusion in metallic nanoparticles, first considering the case of single impurity atoms in matrix clusters, and then on the simulation of the growth in gas phase. We show that diffusion of atoms in nanoparticles can take place by a variety of different mechanisms, which very often involve collective displacements. These collective displacements are facilitated in the vicinity of the cluster surface, which, in small nanoparticles, includes a large portion of the nanoparticle itself.

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Alam, M., e Y. Massoud. "RLC Ladder Model for Scattering in Single Metallic Nanoparticles". IEEE Transactions On Nanotechnology 5, n. 5 (settembre 2006): 491–98. http://dx.doi.org/10.1109/tnano.2006.880403.

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Barber, Angela, Sun Kly, Matthew G. Moffitt, Logan Rand e James F. Ranville. "Coupling single particle ICP-MS with field-flow fractionation for characterizing metal nanoparticles contained in nanoplastic colloids". Environmental Science: Nano 7, n. 2 (2020): 514–24. http://dx.doi.org/10.1039/c9en00637k.

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Composite particles containing metallic nanoparticles in a polymer matrix, which simulate environmentally-transformed nanoparticles, are effectively characterized by combining field-flow fractionation with single particle ICP-MS.

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Roa, Rafael, Stefano Angioletti-Uberti, Yan Lu, Joachim Dzubiella, Francesco Piazza e Matthias Ballauff. "Catalysis by Metallic Nanoparticles in Solution: Thermosensitive Microgels as Nanoreactors". Zeitschrift für Physikalische Chemie 232, n. 5-6 (24 maggio 2018): 773–803. http://dx.doi.org/10.1515/zpch-2017-1078.

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Abstract Metallic nanoparticles have been used as catalysts for various reactions, and the huge literature on the subject is hard to overlook. In many applications, the nanoparticles must be affixed to a colloidal carrier for easy handling during catalysis. These “passive carriers” (e.g. dendrimers) serve for a controlled synthesis of the nanoparticles and prevent coagulation during catalysis. Recently, hybrids from nanoparticles and polymers have been developed that allow us to change the catalytic activity of the nanoparticles by external triggers. In particular, single nanoparticles embedded in a thermosensitive network made from poly(N-isopropylacrylamide) (PNIPAM) have become the most-studied examples of such hybrids: immersed in cold water, the PNIPAM network is hydrophilic and fully swollen. In this state, hydrophilic substrates can diffuse easily through the network, and react at the surface of the nanoparticles. Above the volume transition located at 32°C, the network becomes hydrophobic and shrinks. Now hydrophobic substrates will preferably diffuse through the network and react with other substrates in the reaction catalyzed by the enclosed nanoparticle. Such “active carriers”, may thus be viewed as true nanoreactors that open new ways for the use of nanoparticles in catalysis. In this review, we give a survey on recent work done on these hybrids and their application in catalysis. The aim of this review is threefold: we first review hybrid systems composed of nanoparticles and thermosensitive networks and compare these “active carriers” to other colloidal and polymeric carriers (e.g. dendrimers). In a second step we discuss the model reactions used to obtain precise kinetic data on the catalytic activity of nanoparticles in various carriers and environments. These kinetic data allow us to present a fully quantitative comparison of different nanoreactors. In a final section we shall present the salient points of recent efforts in the theoretical modeling of these nanoreactors. By accounting for the presence of a free-energy landscape for the reactants’ diffusive approach towards the catalytic nanoparticle, arising from solvent-reactant and polymeric shell-reactant interactions, these models are capable of explaining the emergence of all the important features observed so far in studies of nanoreactors. The present survey also suggests that such models may be used for the design of future carrier systems adapted to a given reaction and solvent.

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Jensen, Rebecca A., Jennifer Sherin e Steven R. Emory. "Single Nanoparticle Based Optical pH Probe". Applied Spectroscopy 61, n. 8 (agosto 2007): 832–38. http://dx.doi.org/10.1366/000370207781540105.

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This paper describes the development of a nanoscale optical pH probe based upon the surface-enhanced Raman scattering (SERS) properties of silica–gold core-shell nanoparticles. In this approach, a thin layer of gold is deposited onto a core of silica to form a metallic nanoshell with surface plasmon modes in the red-to-near-infrared spectral region. The surface of the nanoshell is functionalized with a pH-sensitive SERS reporter molecule, 4-mercaptopyridine (4-MPy). The SERS spectra of 4-MPy is shown to be sensitive to the pH of the surrounding media within the range of 3 to 7. In addition, it is shown that individual silica–gold core-shell nanoparticles yield more reliable SERS spectra than aggregates of core-shell nanoparticles.

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Qureshi, Zubair Akbar, Sardar Bilal, Imtiaz Ali Shah, Ali Akgül, Rabab Jarrar, Hussein Shanak e Jihad Asad. "Computational Analysis of the Morphological Aspects of Triadic Hybridized Magnetic Nanoparticles Suspended in Liquid Streamed in Coaxially Swirled Disks". Nanomaterials 12, n. 4 (17 febbraio 2022): 671. http://dx.doi.org/10.3390/nano12040671.

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Currently, pagination clearly explains the increase in the thermophysical attributes of viscous hybrid nanofluid flow by varying morphological aspects of inducted triadic magnetic nanoparticles between two coaxially rotating disks. Copper metallic nanoparticles are inserted with three different types of metallic oxide nanoparticles: Al2O3, Ti2O, and Fe3O4. Single-phase simulation has been designed for the triadic hybrid nanofluids flow. The achieved expressions are transmuted by the obliging transformation technique because of dimensionless ordinary differential equations (ODEs). Runge–Kutta in collaboration with shooting procedure are implemented to achieve the solution of ODEs. The consequences of pertinent variables on associated distributions and related quantities of physical interest are elaborated in detail. It is inferred from the analysis that Cu-Al2O3 metallic type hybrid nanofluids flow shows significant results as compared with the other hybrid nanoparticles. The injection phenomenon on hybrid nanofluids gives remarkable results regarding shear stress and heat flux with the induction of hybridized metallic nanoparticles. Shape and size factors have also been applied to physical quantities. The morphology of any hybrid nanoparticles is directly proportional to the thermal conductance of nanofluids. Peclet number has a significant effect on the temperature profile.

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Yao, Yonggang, Fengjuan Chen, Anmin Nie, Steven D. Lacey, Rohit Jiji Jacob, Shaomao Xu, Zhennan Huang et al. "In Situ High Temperature Synthesis of Single-Component Metallic Nanoparticles". ACS Central Science 3, n. 4 (13 aprile 2017): 294–301. http://dx.doi.org/10.1021/acscentsci.6b00374.

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Sönnichsen, C., S. Geier, N. E. Hecker, G. von Plessen, J. Feldmann, H. Ditlbacher, B. Lamprecht et al. "Spectroscopy of single metallic nanoparticles using total internal reflection microscopy". Applied Physics Letters 77, n. 19 (6 novembre 2000): 2949–51. http://dx.doi.org/10.1063/1.1323553.

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Ernult, F., S. Mitani, K. Takanashi, Y. K. Takahashi e K. Hono. "Self-assembled metallic nanoparticles for spin dependent single electron tunneling". Phase Transitions 79, n. 9-10 (settembre 2006): 717–26. http://dx.doi.org/10.1080/01411590600961222.

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Yannopapas, Vassilios. "An atomistic-electrodynamics theory for the optical response of periodic lattices of metallic nanoparticles in the quantum size regime". International Journal of Modern Physics B 31, n. 24 (30 settembre 2017): 1740001. http://dx.doi.org/10.1142/s021797921740001x.

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We present a new theoretical method for calculating the optical properties of periodic arrays of metallic nanoparticles whose dimensions are in the quantum-size limit and cannot, therefore, be described by macroscopic electrodynamic theory based on Maxwell’s equations. In the first stage, the method calculates the scattering matrix for a single metal nanoparticle described as a polyhedral cluster of atoms, via a discrete-dipole approximation/point-matching technique. The resulting scattering matrix is incorporated into a layer-multiple-scattering technique which allows the modeling of two- and three-dimensional nanostructures containing very small metal nanoparticles. The method is demonstrated for square arrays of silver nanoparticles with radii below 2 nm and the corresponding results are compared against classical local and nonlocal electrodynamic approaches.

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Al-Zubeidi, Alexander, Lauren A. McCarthy, Ali Rafiei-Miandashti, Thomas S. Heiderscheit e Stephan Link. "Single-particle scattering spectroscopy: fundamentals and applications". Nanophotonics 10, n. 6 (8 marzo 2021): 1621–55. http://dx.doi.org/10.1515/nanoph-2020-0639.

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Abstract Metallic nanoparticles supporting a localized surface plasmon resonance have emerged as promising platforms for nanoscopic labels, sensors, and (photo-) catalysts. To use nanoparticles in these capacities, and to gain mechanistic insight into the reactivity of inherently heterogeneous nanoparticles, single-particle characterization approaches are needed. Single-particle scattering spectroscopy has become an important, highly sensitive tool for localizing single plasmonic nanoparticles and studying their optical properties, local environment, and reactivity. In this review, we discuss approaches taken for collecting the scattered light from single particles, their advantages and disadvantages, and present some recent applications. We introduce techniques for the excitation and detection of single-particle scattering such as high-angle dark-field excitation, total internal reflection dark-field excitation, scanning near-field microscopy, and interferometric scattering. We also describe methods to achieve polarization-resolved excitation and detection. We then discuss different approaches for scanning, ratiometric, snapshot, and interferometric hyperspectral imaging techniques used to extract spectral information. Finally, we provide a brief overview of specialized setups for in situ measurements of nanoparticles in liquid systems and setups coupled to scanning tip microscopes.

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Lee, Heon, Jaegu Park, Young-Kwon Park, Byung-Joo Kim, Kay-Hyeok An, Sang-Chai Kim e Sang-Chul Jung. "Preparation and Characterization of Silver-Iron Bimetallic Nanoparticles on Activated Carbon Using Plasma in Liquid Process". Nanomaterials 11, n. 12 (14 dicembre 2021): 3385. http://dx.doi.org/10.3390/nano11123385.

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The mono and bi-metallic nanoparticles have conspicuous properties and are widely used in the environment, energy, and medical fields. In this study, bimetallic nanoparticles composed of silver and iron were precipitated on the surface of activated carbon in a single process using plasma in liquid process (PLP). Silver-iron ions and various radicals were actively generated in the aqueous reactant solution by the PLP. Although metals were precipitated on AC depending on the number of precursors added to the aqueous reactant solution, the standard reduction potential of silver ions was higher than that of iron ions, so silver precipitated on AC. The silver precipitate on AC was a mixture of metallic silver and silver oxide, and iron was present as Fe3O4. Spherical nanoparticles, 100–120 nm in size, were observed on the surface of the Ag-Fe/AC composite. The composition of the bimetallic nanoparticles could be controlled by considering the ionization tendency and standard reduction potential of metal ions and controlling the concentration of the precursors. The PLP presented in this study can be applied to the preparing method of bimetallic nanoparticle/carbon materials and can be expected to be used in the prepare of energy and environmental materials such as MFC and absorption materials for removing pollutants.

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Lee, Hongki, Joel Berk, Aaron Webster, Donghyun Kim e Matthew R. Foreman. "Label-free detection of single nanoparticles with disordered nanoisland surface plasmon sensor". Nanotechnology 33, n. 16 (24 gennaio 2022): 165502. http://dx.doi.org/10.1088/1361-6528/ac43e9.

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Abstract We report sensing of single nanoparticles using disordered metallic nanoisland substrates supporting surface plasmon polaritons (SPPs). Speckle patterns arising from leakage radiation of elastically scattered SPPs provide a unique fingerprint of the scattering microstructure at the sensor surface. Experimental measurements of the speckle decorrelation are presented and shown to enable detection of sorption of individual gold nanoparticles and polystyrene beads. Our approach is verified through bright-field and fluorescence imaging of particles adhering to the nanoisland substrate.

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Li, Hongze, Zhihe Yang, Sadaf Aiman Khan, Laurence J. Walsh, Chaminda Jayampath Seneviratne e Zyta M. Ziora. "Characteristics of Metallic Nanoparticles (Especially Silver Nanoparticles) as Anti-Biofilm Agents". Antibiotics 13, n. 9 (28 agosto 2024): 819. http://dx.doi.org/10.3390/antibiotics13090819.

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Biofilm-associated infections account for a large proportion of chronic diseases and pose a major health challenge. Metal nanoparticles offer a new way to address this problem, by impairing microbial growth and biofilm formation and by causing degradation of existing biofilms. This review of metal nanoparticles with antimicrobial actions included an analysis of 20 years of journal papers and patent applications, highlighting the progress over that time. A network analysis of relevant publications showed a major focus on the eradication of single-species biofilms formed under laboratory conditions, while a bibliometric analysis showed growing interest in combining different types of metal nanoparticles with one another or with antibiotics. The analysis of patent applications showed considerable growth over time, but with relatively few patents progressing to be granted. Overall, this profile shows that intense interest in metal nanoparticles as anti-biofilm agents is progressing beyond the confines of simple laboratory biofilm models and coming closer to clinical application. Looking to the future, metal nanoparticles may provide a sustainable approach to combatting biofilms of drug-resistant bacteria.

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Auad, Yves, Cyrille Hamon, Marcel Tencé, Hugo Lourenço-Martins, Vahagn Mkhitaryan, Odile Stéphan, F. Javier García de Abajo, Luiz H. G. Tizei e Mathieu Kociak. "Unveiling the Coupling of Single Metallic Nanoparticles to Whispering-Gallery Microcavities". Nano Letters 22, n. 1 (15 dicembre 2021): 319–27. http://dx.doi.org/10.1021/acs.nanolett.1c03826.

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Tomchuk, Petro M., e Danylo Butenko. "Single and double ultrashort laser pulse scattering by spheroidal metallic nanoparticles". Journal of Nanophotonics 10, n. 1 (29 marzo 2016): 016018. http://dx.doi.org/10.1117/1.jnp.10.016018.

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Mamonova, Daria V., Anna A. Vasileva, Yuri V. Petrov, Alexandra V. Koroleva, Denis V. Danilov, Ilya E. Kolesnikov, Gulia I. Bikbaeva, Julien Bachmann e Alina A. Manshina. "Single Step Laser-Induced Deposition of Plasmonic Au, Ag, Pt Mono-, Bi- and Tri-Metallic Nanoparticles". Nanomaterials 12, n. 1 (31 dicembre 2021): 146. http://dx.doi.org/10.3390/nano12010146.

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Multimetallic plasmonic systems usually have distinct advantages over monometallic nanoparticles due to the peculiarity of the electronic structure appearing in advanced functionality systems, which is of great importance in a variety of applications including catalysis and sensing. Despite several reported techniques, the controllable synthesis of multimetallic plasmonic nanoparticles in soft conditions is still a challenge. Here, mono-, bi- and tri-metallic nanoparticles were successfully obtained as a result of a single step laser-induced deposition approach from monometallic commercially available precursors. The process of nanoparticles formation is starting with photodecomposition of the metal precursor resulting in nucleation and the following growth of the metal phase. The deposited nanoparticles were studied comprehensively with various experimental techniques such as SEM, TEM, EDX, XPS, and UV-VIS absorption spectroscopy. The size of monometallic nanoparticles is strongly dependent on the type of metal: 140–200 nm for Au, 40–60 nm for Ag, 2–3 nm for Pt. Bi- and trimetallic nanoparticles were core-shell structures representing monometallic crystallites surrounded by an alloy of respective metals. The formation of an alloy phase took place between monometallic nanocrystallites of different metals in course of their growth and agglomeration stage.

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31

Hamans, Ruben F., Rifat Kamarudheen e Andrea Baldi. "Single Particle Approaches to Plasmon-Driven Catalysis". Nanomaterials 10, n. 12 (29 novembre 2020): 2377. http://dx.doi.org/10.3390/nano10122377.

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Plasmonic nanoparticles have recently emerged as a promising platform for photocatalysis thanks to their ability to efficiently harvest and convert light into highly energetic charge carriers and heat. The catalytic properties of metallic nanoparticles, however, are typically measured in ensemble experiments. These measurements, while providing statistically significant information, often mask the intrinsic heterogeneity of the catalyst particles and their individual dynamic behavior. For this reason, single particle approaches are now emerging as a powerful tool to unveil the structure-function relationship of plasmonic nanocatalysts. In this Perspective, we highlight two such techniques based on far-field optical microscopy: surface-enhanced Raman spectroscopy and super-resolution fluorescence microscopy. We first discuss their working principles and then show how they are applied to the in-situ study of catalysis and photocatalysis on single plasmonic nanoparticles. To conclude, we provide our vision on how these techniques can be further applied to tackle current open questions in the field of plasmonic chemistry.

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32

Xue, Huan-Huan, Wen-Jin Shen, Wen-Chao Geng, Xia Yin, Yue Yang, Shaojun Guo e Yong-Jun Li. "Asymmetrical etching of Ag nanoparticles into symmetry-reduced bi-metallic nanocups at the single-nanoparticle level". Chemical Communications 54, n. 52 (2018): 7227–30. http://dx.doi.org/10.1039/c8cc03491e.

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By employing the water/air interface-confinement effect, local nanomasking and thus selective etching were achieved on single interfacial nanoparticles, developing a series of symmetry-reduced cubic, spherical, trough-like nanocups.

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33

Weis, Martin, Katarína Gmucová, Vojtech Nádaždy, Ignác Capek, Alexander Šatka, Martin Kopáni, Július Cirák e Eva Majková. "Control of Single-Electron Charging of Metallic Nanoparticles onto Amorphous Silicon Surface". Journal of Nanoscience and Nanotechnology 8, n. 11 (1 novembre 2008): 5684–89. http://dx.doi.org/10.1166/jnn.2008.214.

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Sequential single-electron charging of iron oxide nanoparticles encapsulated in oleic acid/oleyl amine envelope and deposited by the Langmuir-Blodgett technique onto Pt electrode covered with undoped hydrogenated amorphous silicon film is reported. Single-electron charging (so-called quantized double-layer charging) of nanoparticles is detected by cyclic voltammetry as current peaks and the charging effect can be switched on/off by the electric field in the surface region induced by the excess of negative/positive charged defect states in the amorphous silicon layer. The particular charge states in amorphous silicon are created by the simultaneous application of a suitable bias voltage and illumination before the measurement. The influence of charged states on the electric field in the surface region is evaluated by the finite element method. The single-electron charging is analyzed by the standard quantized double layer model as well as two weak-link junctions model. Both approaches are in accordance with experiment and confirm single-electron charging by tunnelling process at room temperature. This experiment illustrates the possibility of the creation of a voltage-controlled capacitor for nanotechnology.

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Vijayan, Vineeth M., Pradipika Natamai Vasudevan e Vinoy Thomas. "Polymeric Nanogels for Theranostic Applications: A Mini-Review". Current Nanoscience 16, n. 3 (2 aprile 2020): 392–98. http://dx.doi.org/10.2174/1573413715666190717145040.

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Theranostics is a recently emerging area in nanomedicine. Nanoparticles which can combine both diagnostic and therapy in one single platform serve as theranostic agents. Some of the currently explored nanoparticles are metallic nanoparticles, mesoporous silica nanoparticles, carbonbased nanoparticles, and polymer nanogels. Polymeric nanogels are receiving considerable attention due to their high biocompatibility and functional performance. The present review article briefly summarizes the scopes and challenges of the state of art of using polymeric nanogels for theranostic applications. Among the different polymer nanogels, a special emphasis is given to polymeric nanogels with innate imaging potential.

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35

NAIR, A. SREEKUMARAN, RENJIS T. TOM, V. R. RAJEEV KUMAR, C. SUBRAMANIAM e T. PRADEEP. "CHEMICAL INTERACTIONS AT NOBLE METAL NANOPARTICLE SURFACES — CATALYSIS, SENSORS AND DEVICES". COSMOS 03, n. 01 (novembre 2007): 103–24. http://dx.doi.org/10.1142/s0219607707000244.

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In this paper, a summary of some of the recent research efforts in our laboratory on chemical interactions at noble metal nanoparticle surfaces is presented. The article is divided into five sections, detailing with (i) interactions of simple halocarbons with gold and silver nanoparticle surfaces at room temperature by a new chemistry and the exploitation of this chemistry in the extraction of pesticides from drinking water, (ii) interaction of biologically important proteins such as Cyt c, hemoglobin and myoglobin as well as a model system, hemin with gold and silver nanoparticles and nanorods forming nano–bio conjugates and their surface binding chemistry, (iii) formation of polymer–nano composites with tunable optical properties and temperature sensing characteristics by single and multi-step methodologies, (iv) nanomaterials-based flow sensors and (v) composites of noble metal nanoparticles and metallic carbon nanotubes showing visible fluorescence induced by metal–semiconductor transition.

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36

Park, Joohyuk, Marcel Risch, Gyutae Nam, Minjoon Park, Tae Joo Shin, Suhyeon Park, Min Gyu Kim, Yang Shao-Horn e Jaephil Cho. "Single crystalline pyrochlore nanoparticles with metallic conduction as efficient bi-functional oxygen electrocatalysts for Zn–air batteries". Energy & Environmental Science 10, n. 1 (2017): 129–36. http://dx.doi.org/10.1039/c6ee03046g.

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We have shown that highly efficient metallic pyrochlore oxide nanoparticles (Pb₂Ru₂O_6.5) exhibit outstanding activity as bi-functional electrocatalysts in aqueous Zn–air batteries for ORR and OER.

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37

Pattnaik, P. K., S. K. Parida, S. R. Mishra, M. Ali Abbas e M. M. Bhatti. "Analysis of Metallic Nanoparticles (Cu, Al2O3, and SWCNTs) on Magnetohydrodynamics Water-Based Nanofluid through a Porous Medium". Journal of Mathematics 2022 (14 febbraio 2022): 1–12. http://dx.doi.org/10.1155/2022/3237815.

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In this communication, the effect of the addition of the copper (Cu), aluminum oxide (Al2O3), and single-wall carbon nanotubes (SWCNTs) metallic nanoparticles on the magnetohydrodynamics (MHD) water-based flow over a porous elastic surface is explored. The objective of the work is to include the radiative effect that interacts with the metallic nanoparticles due to permeability of the surface. The significance of this study stems from the fact that the design of various equipment, such as nuclear power plants, gas turbines, propulsion devices for aircraft, and missiles, is dependent on radiative heat transfer. To formulate the mathematical modelling, similarity transformations were used, and nonlinear differential equations were obtained. To solve the formulated nonlinear differential equations, the Runge–Kutta fourth-order numerical scheme is used in conjunction with the shooting technique. The behavior of velocity profile and temperature profile has been discussed in detail and also engineering quantities such as Nusselt and Sherwood number which are calculated. Furthermore, the addition of metallic nanoparticles enhanced the nanofluid properties for energy transfer enrichment and found many applications in various fields of science and technology.

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38

Movsesyan, Artur, Anne-Laure Baudrion e Pierre-Michel Adam. "Extinction measurements of metallic nanoparticles arrays as a way to explore the single nanoparticle plasmon resonances". Optics Express 26, n. 5 (2 marzo 2018): 6439. http://dx.doi.org/10.1364/oe.26.006439.

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39

Pandey, Popular, Javier Garcia, Jing Guo, Xuewen Wang, Dan Yang e Jin He. "Differentiation of metallic and dielectric nanoparticles in solution by single-nanoparticle collision events at the nanoelectrode". Nanotechnology 31, n. 1 (8 ottobre 2019): 015503. http://dx.doi.org/10.1088/1361-6528/ab4445.

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40

Povolotskiy, Alexey V., Oksana S. Smirnova, Diana A. Soldatova, Anastasia V. Povolotckaia e Daniil A. Lukyanov. "High-Precision Optical Excited Heaters Based on Au Nanoparticles and Water-Soluble Porphyrin". Metals 13, n. 11 (5 novembre 2023): 1851. http://dx.doi.org/10.3390/met13111851.

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Abstract (sommario):

Gold nanoparticles are widely used as local heaters under optical excitation. Hybrid molecular-plasmon nanostructures based on gold nanoparticles and water-soluble porphyrin have been developed. A colloidal solution of gold nanoparticles was obtained by laser ablation of metallic gold in water, ensuring its highest chemical purity. The hybrid nanostructures formation was performed due to the Coulomb interaction of cationic porphyrin and gold nanoparticles. The revealed functional properties of hybrid nanostructures make them promising for controllable nano-heater applications (for example, photothermal therapy). Gold nanoparticles act as heaters, whereas porphyrin serves as a fluorescent thermometer with a single optical excitation.

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41

Banerjee, Soham, Chia-Hao Liu, Kirsten M. Ø. Jensen, Pavol Juhás, Jennifer D. Lee, Marcus Tofanelli, Christopher J. Ackerson, Christopher B. Murray e Simon J. L. Billinge. "Cluster-mining: an approach for determining core structures of metallic nanoparticles from atomic pair distribution function data". Acta Crystallographica Section A Foundations and Advances 76, n. 1 (1 gennaio 2020): 24–31. http://dx.doi.org/10.1107/s2053273319013214.

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A novel approach for finding and evaluating structural models of small metallic nanoparticles is presented. Rather than fitting a single model with many degrees of freedom, libraries of clusters from multiple structural motifs are built algorithmically and individually refined against experimental pair distribution functions. Each cluster fit is highly constrained. The approach, called cluster-mining, returns all candidate structure models that are consistent with the data as measured by a goodness of fit. It is highly automated, easy to use, and yields models that are more physically realistic and result in better agreement to the data than models based on cubic close-packed crystallographic cores, often reported in the literature for metallic nanoparticles.

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42

Burkitt, Sean, Mana Mehraein, Ramunas K. Stanciauskas, Jos Campbell, Scott Fraser e Cristina Zavaleta. "Label-Free Visualization and Tracking of Gold Nanoparticles in Vasculature Using Multiphoton Luminescence". Nanomaterials 10, n. 11 (12 novembre 2020): 2239. http://dx.doi.org/10.3390/nano10112239.

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Abstract (sommario):

Gold nanoparticles continue to generate interest for use in several biomedical applications. Recently, researchers have been focusing on exploiting their dual diagnostic/therapeutic theranostic capabilities. Before clinical translation can occur, regulatory agencies will require a greater understanding of their biodistribution and safety profiles post administration. Previously, the real-time identification and tracking of gold nanoparticles in free-flowing vasculature had not been possible without extrinsic labels such as fluorophores. Here, we present a label-free imaging approach to examine gold nanoparticle (AuNP) activity within the vasculature by utilizing multiphoton intravital microscopy. This method employs a commercially available multiphoton microscopy system to visualize the intrinsic luminescent signal produced by a multiphoton absorption-induced luminescence effect observed in single gold nanoparticles at frame rates necessary for capturing real-time blood flow. This is the first demonstration of visualizing unlabeled gold nanoparticles in an unperturbed vascular environment with frame rates fast enough to achieve particle tracking. Nanoparticle blood concentration curves were also evaluated by the tracking of gold nanoparticle flow in vasculature and verified against known pre-injection concentrations. Half-lives of these gold nanoparticle injections ranged between 67 and 140 s. This label-free imaging approach could provide important structural and functional information in real time to aid in the development and effective analysis of new metallic nanoparticles for various clinical applications in an unperturbed environment, while providing further insight into their complex uptake and clearance pathways.

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43

Byers, Chad P., Hui Zhang, Dayne F. Swearer, Mustafa Yorulmaz, Benjamin S. Hoener, Da Huang, Anneli Hoggard et al. "From tunable core-shell nanoparticles to plasmonic drawbridges: Active control of nanoparticle optical properties". Science Advances 1, n. 11 (dicembre 2015): e1500988. http://dx.doi.org/10.1126/sciadv.1500988.

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The optical properties of metallic nanoparticles are highly sensitive to interparticle distance, giving rise to dramatic but frequently irreversible color changes. By electrochemical modification of individual nanoparticles and nanoparticle pairs, we induced equally dramatic, yet reversible, changes in their optical properties. We achieved plasmon tuning by oxidation-reduction chemistry of Ag-AgCl shells on the surfaces of both individual and strongly coupled Au nanoparticle pairs, resulting in extreme but reversible changes in scattering line shape. We demonstrated reversible formation of the charge transfer plasmon mode by switching between capacitive and conductive electronic coupling mechanisms. Dynamic single-particle spectroelectrochemistry also gave an insight into the reaction kinetics and evolution of the charge transfer plasmon mode in an electrochemically tunable structure. Our study represents a highly useful approach to the precise tuning of the morphology of narrow interparticle gaps and will be of value for controlling and activating a range of properties such as extreme plasmon modulation, nanoscopic plasmon switching, and subnanometer tunable gap applications.

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44

Auad, Yves, Cyrille Hamon, Marcel Tencé, H. Lourenço-Matins, Vahagn Mkhitaryan, Odile Stéphan, F. Javier García de Abajo, Luiz H. G. Tizei e Mathieu Kociak. "Unveiling Single Particle Coupling of Metallic Nanoparticles and Whispering Gallery Mode Resonators". Microscopy and Microanalysis 28, S1 (22 luglio 2022): 1962–64. http://dx.doi.org/10.1017/s1431927622007656.

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45

Feng, Yiyu, Peng Lv, Xuequan Zhang, Yu Li e Wei Feng. "Selective electroless coating of palladium nanoparticles on metallic single-walled carbon nanotube". Applied Physics Letters 97, n. 8 (23 agosto 2010): 083101. http://dx.doi.org/10.1063/1.3483615.

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46

Narvaez, G. A., e G. Kirczenow. "Understanding Tunneling Experiments on Metallic Nanoparticles: Single-Particle versus Many-Body Phenomena". physica status solidi (b) 230, n. 2 (aprile 2002): 457–61. http://dx.doi.org/10.1002/1521-3951(200204)230:2<457::aid-pssb457>3.0.co;2-a.

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47

Bruix, Albert, Jeppe V. Lauritsen e Bjørk Hammer. "Effects of particle size and edge structure on the electronic structure, spectroscopic features, and chemical properties of Au(111)-supported MoS2 nanoparticles". Faraday Discussions 188 (2016): 323–43. http://dx.doi.org/10.1039/c5fd00203f.

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Abstract (sommario):

Materials based on MoS₂ are widely used as catalysts and their structure usually consists of single-layered MoS₂ nanoparticles whose edges are known to constitute the catalytically active sites. Methods based on density functional theory are used in this work to calculate the electronic structure of representative computational models of MoS₂ nanoparticles supported on Au(111). By considering nanoparticles with different edge-terminations, compositions, and sizes, we describe how the electronic structure, Mo3d core-level shifts, and chemical properties (i.e. H adsorption and S vacancy formation) depend on the MoS₂ nanoparticle size and structure. In addition, site-specific properties, largely inaccessible when using only slab models of MoS₂ edges, are reported, which reveal that the edge sites are not uniform along the nanoparticle and largely depend on the proximity to the corners of the triangular NPs, especially when interacting with a metallic support. Furthermore, a structural motif where H atoms adsorb favourably in a bridging position between two Mo atoms is proposed as an active site for the hydrogen evolution reaction.

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48

Vakhitov, Iskander R., Nikolay M. Lyadov, Vladimir I. Vdovin, Anton K. Gutakovskii, Vladimir I. Nuzhdin, Lenar R. Tagirov e Rustam I. Khaibullin. "Ion-Beam Synthesis of Structure-Oriented Iron Nanoparticles in Single-Crystalline Rutile TiO2". Crystals 13, n. 2 (18 febbraio 2023): 355. http://dx.doi.org/10.3390/cryst13020355.

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Magnetic nanoparticles embedded into semiconductors have current perspectives for use in semiconducting spintronics. In this work, 40 keV Fe+ ions were implanted in high fluences of (0.5 ÷ 1.5) × 1017 ion/cm2 into an oxide semiconductor and single-crystalline TiO2 plates of rutile structure with (100) or (001) face orientations. Microstructure, elemental-phase composition, and magnetic properties of the Fe-ion-implanted TiO2 were studied by scanning and transmission electron microscopies (SEM and TEM), X-ray photoelectron (XPS) and Rutherford backscattering (RBS) spectroscopies, as well as vibrating-sample magnetometry (VSM). The high-fluence ion implantation results in the formation of magnetic nanoparticles of metallic iron beneath the irradiated surface of rutile. The induced ferromagnetism and observed two- or four-fold magnetic anisotropy are associated with the endotaxial growth of Fe nanoparticles oriented along the crystallographic axes of TiO2.

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49

Chook, Soon Wei, Chin Hua Chia, Zakaria Sarani, Mohd Khan Ayob, Kah Leong Chee, Hui Min Neoh e Nay Ming Huang. "Silver Nanoparticles - Graphene Oxide Nanocomposite for Antibacterial Purpose". Advanced Materials Research 364 (ottobre 2011): 439–43. http://dx.doi.org/10.4028/www.scientific.net/amr.364.439.

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Graphene oxide (GO) sheets, a single layer of carbon atoms which can be served as substrates for fabricating metallic nanoparticles-GO nanocomposites. In this study, the nanocomposite of silver nanoparticles and graphene oxide were produced via in-situ synthesis and with the addition of chitosan to investigate the formation of silver nanoparticles on the graphene oxide sheets. XRD and UV-Vis studies confirmed the formation of silver nanoparticles on GO sheets, while TEM and FESEM images presented the loading of silver nanoparticles on the GO sheets. The degree of loading and distribution of the silver nanoparticles on the graphene oxide were depend on the method during the formation of silver nanoparticles. The nanocomposites can be potentially used in food packaging and biomedical applications.

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Konopatsky, Anton S., Vladislava V. Kalinina, Danil V. Barilyuk e Dmitri V. Shtansky. "Polyol Synthesis of Bimetallic FePt Nanoparticles over h-BN Substrate". Materials Science Forum 1128 (28 ottobre 2024): 51–56. http://dx.doi.org/10.4028/p-jz9wev.

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Hexagonal boron nitride (h-BN) is a promising support for the deposition of functional metallic nanoparticles for next generation of catalysts. Multicomponent metallic NPs, such as bimetallic FePt NPs, are attracting much attention as catalytically active sites because their properties can be superior to their single-element counterpart. To achieve the best catalytic properties, careful control of the chemical composition of the bimetallic NPs on the surface of h-BN substrates is necessary. Herein we report the development of a polyol synthesis protocol that elucidates the relationship between the initial and resulting Fe:Pt molar ratio in a FePt/h-BN material. TEM, STEM, EDXS, BET and BJH methods were utilized to characterize the surface and structure of the h-BN support and FePt/h-BN heterostructures.

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