The Experts below are selected from a list of 21624 Experts worldwide ranked by ideXlab platform
Fabien Grasset - One of the best experts on this subject based on the ideXlab platform.
-
New ultra-violet and near-infrared blocking filters for energy saving applications: fabrication of tantalum metal Atom Cluster-based nanocomposite thin films by electrophoretic deposition
Journal of Materials Chemistry C, 2017Co-Authors: Thi Kim Ngan Nguyen, Stéphane Cordier, Benjamin Dierre, Adele Renaud, Maxence Wilmet, Noee Dumait, Serge Paofai, Wanghui Chen, Naoki Ohashi, Fabien GrassetAbstract:This study reports the first integration of inorganic tantalum octahedral metal Atom Clusters into multifunctional nanocomposite coating materials and devices for window technology and energy saving applications. [Ta6Br12i](n+) (n = 2, 3 or 4) Cluster-based high visible transparency UV and NIR filters are realized. Green and brown colored films are fabricated by coating on an indium-doped tin oxide glass substrate by electrophoretic deposition, an industrialized solution process. The efficiency in energy saving of the new UV-NIR filters was estimated by the determination of different figure of merit (FOM) values, such as Tvis, Tsol and Tvis/Tsol (Tsol = solar transmittance and Tvis = visible transmittance), and the color coordinates (x, y, z and L*a*b). The Tvis/Tsol ratio is equal to 1.25 for the best films. Such values are evidence of a higher energy saving efficiency than most of the inorganic composites reported in the literature. These promising results pave the way for the use of transition metal Clusters as a new class of nanocoatings in energy saving window-based applications.
-
advances in the engineering of near infrared emitting liquid crystals and copolymers extended porous frameworks theranostic tools and molecular junctions using tailored re6 Cluster building blocks
Journal of Cluster Science, 2015Co-Authors: Stéphane Cordier, Fabien Grasset, Yann Molard, Konstantin A Brylev, Yuri V Mironov, Bruno Fabre, N G NaumovAbstract:At the occasion of the fiftieth birthday of the introduction of the term ‘metal Atom Cluster’ by F. A. Cotton in inorganic chemistry, it is the good time to make a review on the advances in the engineering of molecular assemblies and nanomaterials based on octahedral Re6 metal Atom Clusters. The latter exhibit unique intrinsic structural and physicochemical properties (orthogonal disposition of metallic sites that can be selectively functionalized, photoluminescence, redox, generation of singlet oxygen) that make them relevant building blocks for the structuration at the nanometric scale and functionalization of hybrid organic–inorganic materials and supramolecular frameworks. After synthesis by solid state chemistry techniques at high temperature, inorganic precursors built up on face-capped \(\left[ {\left( {{\text{Re}}_{ 6} {\text{Y}}_{ 8}^{\text{i}} } \right){\text{Y}}_{ 6}^{\text{a}} } \right]\) Cluster units (Y = chalcogen and/or halogen) can be functionalized via solution chemistry techniques or organic melts to form \(\left[ {\left( {{\text{Re}}_{ 6} {\text{Y}}_{ 8}^{\text{i}} } \right){\text{L}}_{ 6}^{\text{a}} } \right]\) (L = CN, OH, various organic ligands…). This work reports advances in the synthesis of \(\left[ {\left( {{\text{Re}}_{ 6} {\text{Y}}_{ 8}^{\text{i}} } \right){\text{Y}}_{ 6}^{\text{a}} } \right]\) and \(\left[ {\left( {{\text{Re}}_{ 6} {\text{Y}}_{ 8}^{\text{i}} } \right){\text{L}}_{ 6}^{\text{a}} } \right]\) Cluster units as well as on their use in the elaboration of supramolecular frameworks, nanoparticles, hybrid nanomaterials (co-polymers and liquid crystals) and active molecular junctions.
M Kira - One of the best experts on this subject based on the ideXlab platform.
-
hyperbolic bloch equations Atom Cluster kinetics of an interacting bose gas
Annals of Physics, 2015Co-Authors: M KiraAbstract:Abstract Experiments with ultracold Bose gases can already produce so strong Atom–Atom interactions that one can observe intriguing many-body dynamics between the Bose–Einstein condensate (BEC) and the non-condensed Atoms. This dynamics is thoroughly analyzed with the Cluster-expansion approach to uniquely identify Atom-Cluster dynamics within the many-body system. These Clusters assign those Atoms that are genuinely connected with one another. The excitation picture is applied to express the many-body state in terms of correlated Atom Clusters among the non-condensed Atoms alone. Implicit notation formalism is developed to explicitly derive the quantum kinetics of all Atom Clusters. The Clusters are shown to build up sequentially, from smaller to larger ones, which is utilized to nonperturbatively describe the interacting BEC with as few Clusters as possible. This yields the hyperbolic Bloch equations (HBEs) that not only generalize the Hartree–Fock Bogoliubov approach but are also analogous to the semiconductor Bloch equations (SBEs). This connection is utilized to apply sophisticated many-body techniques of semiconductor quantum optics to BEC investigations. Here, the HBEs are implemented to determine how a strongly interacting Bose gas reacts to a fast switching from weak to strong interactions, often referred to as unitarity. The computations for 85 Rb demonstrate that molecular states (dimers) depend on Atom density, and that the many-body interactions create coherent transients on a 100 μ s time scale converting BEC into non-condensed Atoms via quantum depletion.
-
hyperbolic bloch equations Atom Cluster kinetics of an interacting bose gas
arXiv: Quantum Gases, 2014Co-Authors: M KiraAbstract:Experiments with ultracold Bose gases can already produce so strong Atom--Atom interactions that one can observe intriguing many-body dynamics between the Bose-Einstein condensate (BEC) and the normal component. The excitation picture is applied to uniquely express the many-body state uniquely in terms of correlated Atom Clusters within the normal component alone. Implicit notation formalism is developed to {\it explicitly} derive the quantum kinetics of {\it all} Atom Clusters. The Clusters are shown to build up sequentially, from smaller to larger ones, which is utilized to nonperturbatively describe the interacting BEC with as few Clusters as possible. This yields the hyperbolic Bloch equations (HBEs) that not only generalize the Hartree-Fock Bogoliubov approach but also are analogous to the semiconductor Bloch equations (SBEs). This connection is utilized to apply sophisticated many-body techniques of semiconductor quantum optics to BEC investigations. Here, the HBEs are implemented to determine how a strongly interacting Bose gas reacts to a fast switching from weak to strong interactions, often referred to as unitarity. The computations for $^{35}$Rb demonstrate that molecular states (dimers) depend on Atom density, and that the many-body interactions create coherent transients on a 100$\mu$s time scale converting BEC into normal state via quantum depletion.
Jun Lou - One of the best experts on this subject based on the ideXlab platform.
-
enhanced performance of in plane transition metal dichalcogenides monolayers by configuring local Atomic structures
Nature Communications, 2020Co-Authors: Yao Zhou, Wu Zhou, Jing Zhang, Erhong Song, Junhao Lin, Jiadong Zhou, Kazu Suenaga, Zheng Liu, Jianjun Liu, Jun LouAbstract:The intrinsic activity of in-plane chalcogen Atoms plays a significant role in the catalytic performance of transition metal dichalcogenides (TMDs). A rational modulation of the local configurations is essential to activating the in-plane chalcogen Atoms but restricted by the high energy barrier to break the in-plane TM-X (X = chalcogen) bonds. Here, we theoretically design and experimentally realize the tuning of local configurations. The electron transfer capacity of local configurations is used to screen suitable TMDs materials for hydrogen evolution reaction (HER). Among various configurations, the triangular-shape cobalt Atom Cluster with a central sulfur vacancy (3CoMo-VS) renders the distinct electrocatalytic performance of MoS2 with much reduced overpotential and Tafel slope. The present study sheds light on deeper understanding of Atomic-scale local configuration in TMDs and a methodology to boost the intrinsic activity of chalcogen Atoms. Designing and realizing local configurations can activate the in-plane chalcogen Atoms of transition metal dichalcogenide to enhance the HER activity. We combine the theoretical screening (charge transfer capability) and experimental realization to achieve highly active local configurations
Thi Kim Ngan Nguyen - One of the best experts on this subject based on the ideXlab platform.
-
New ultra-violet and near-infrared blocking filters for energy saving applications: fabrication of tantalum metal Atom Cluster-based nanocomposite thin films by electrophoretic deposition
Journal of Materials Chemistry C, 2017Co-Authors: Thi Kim Ngan Nguyen, Stéphane Cordier, Benjamin Dierre, Adele Renaud, Maxence Wilmet, Noee Dumait, Serge Paofai, Wanghui Chen, Naoki Ohashi, Fabien GrassetAbstract:This study reports the first integration of inorganic tantalum octahedral metal Atom Clusters into multifunctional nanocomposite coating materials and devices for window technology and energy saving applications. [Ta6Br12i](n+) (n = 2, 3 or 4) Cluster-based high visible transparency UV and NIR filters are realized. Green and brown colored films are fabricated by coating on an indium-doped tin oxide glass substrate by electrophoretic deposition, an industrialized solution process. The efficiency in energy saving of the new UV-NIR filters was estimated by the determination of different figure of merit (FOM) values, such as Tvis, Tsol and Tvis/Tsol (Tsol = solar transmittance and Tvis = visible transmittance), and the color coordinates (x, y, z and L*a*b). The Tvis/Tsol ratio is equal to 1.25 for the best films. Such values are evidence of a higher energy saving efficiency than most of the inorganic composites reported in the literature. These promising results pave the way for the use of transition metal Clusters as a new class of nanocoatings in energy saving window-based applications.
Hansgeorg Schnockel - One of the best experts on this subject based on the ideXlab platform.
-
monitoring the dissolution process of metals in the gas phase reactions of nanoscale al and ga metal Atom Clusters and their relationship to similar metalloid Clusters
Chemical Communications, 2008Co-Authors: Ralf Burgert, Hansgeorg SchnockelAbstract:Formation and dissolution of metals are two of the oldest technical chemical processes. On the Atomic scale, these processes are based on the formation and cleavage of metal–metal bonds. During the past 15 years we have studied intensively the intermediates during the formation process of metals, i.e. the formation of compounds containing many metal–metal bonds between naked metal Atoms in the center and ligand-bearing metal Atoms at the surface. We have called the Clusters metalloid or, more generally, elementoid Clusters. Via a retrosynthetic route, the many different Al and Ga metalloid Clusters which have been structurally characterized allow us to understand also the dissolution process; i.e. the cleavage of metal–metal (M–M) bonds. However, this process can be detected much more directly by the reaction of single metal Atom Clusters in the gas phase under high vacuum conditions. A suitable tool to monitor the dissolution process of a metal Cluster in the gas phase is FT-ICR (Fourier transform ion cyclotron resonance) mass spectrometry. Snapshots during these cleavage processes are possible because only every 1–10 s is there a contact between a Cluster molecule and an oxidizing molecule (e.g. Cl2). This period is long, i.e. the formation of the primary product (a smaller metal Atom Cluster) is finished before the next collision happens. We have studied three different types of reaction:(1) Step-by-step fragmentation of a structurally known metalloid Cluster allows us to understand the bonding principle of these Clusters because in every step only the weakest bond is broken.(2) There are three oxidation reactions of an Al13− Cluster molecule with Cl2, HCl and O2 central to this review. These three reactions represent three different reaction types, (a) an exothermic reaction (Cl2), (b) an endothermic reaction (HCl), and (c) a kinetically limited reaction based on spin conservation rules (O2).(3) Finally, we present the reaction of a metalloid Cluster with Cl2 in order to show that in this Cluster only the central naked metal Atoms are oxidized, and a smaller metalloid Cluster results containing the entire protecting shell as the primary Cluster.All the experimental results, supported by quantum chemical calculations, give a rough idea about the complex reaction cascades which occur during the dissolution and formation of metals. Furthermore, these results cast a critical light on many simplifying and generalizing rules in order to understand the bonding and structure of metal Clusters. Finally, the experiments and some recent results provided by physical measurements on a crystalline Ga84 compound build a bridge to nanoscience; i.e. they may be a challenge for chemistry in the next decades, since it has been shown that only with a perfect orientation of nanoscale metal Clusters, e.g. in a crystal, can novel, unexpected properties (e.g. superconducting nanoscale materials) be obtained.