The Experts below are selected from a list of 294 Experts worldwide ranked by ideXlab platform
Ludwig Bartels - One of the best experts on this subject based on the ideXlab platform.
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Tailoring molecular layers at Metal Surfaces
Nature Chemistry, 2010Co-Authors: Ludwig BartelsAbstract:The formation of single-layer-thick molecular networks at Metal Surfaces is governed by the interplay between intermolecular and interfacial interactions. This Review highlights how, with films built by vacuum deposition, these interactions can be modulated to form substrates that may be useful as catalysts or templates for further deposition steps. The design of networks of organic molecules at Metal Surfaces, highly attractive for a variety of applications ranging from molecular electronics to gas sensors to protective coatings, has matured to a degree that patterns with multinanometre unit cells and almost any arbitrary geometry can be fabricated. This Review provides an overview of vacuum-deposited organic networks at Metal Surfaces, using intermolecular hydrogen bonding, Metal–atom coordination and in situ polymerization. Recent progress in these areas highlights how the design of surface patterns can benefit from the wealth of information available from solution- and bulk-phase chemistry, while at the same time providing novel insights into the nature of such bonds through the applicability of direct scanning probe imaging at Metal Surfaces.
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tailoring molecular layers at Metal Surfaces
Nature Chemistry, 2010Co-Authors: Ludwig BartelsAbstract:The formation of single-layer-thick molecular networks at Metal Surfaces is governed by the interplay between intermolecular and interfacial interactions. This Review highlights how, with films built by vacuum deposition, these interactions can be modulated to form substrates that may be useful as catalysts or templates for further deposition steps.
Armand P Alivisatos - One of the best experts on this subject based on the ideXlab platform.
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semiconductor nanocrystals covalently bound to Metal Surfaces with self assembled monolayers
Journal of the American Chemical Society, 1992Co-Authors: Vicki L. Colvin, A. N. Goldstein, Armand P AlivisatosAbstract:A method is described for attaching semiconductor nanocrystals to Metal Surfaces using self-assembled difunctional organic monolayers as bridge compounds. Three different techniques are presented. Two rely on the formation of self-assembled monolayers on gold and aluminum in which the exposed tail groups are thiols. When exposed to heptane solutions of cadmium-rich nanocrystals, these free thiols bind the cadmium and anchor it to the surface. The third technique attaches nanocrystals already coated with carboxylic acids to freshly cleaned aluminum. The nanocrystals, before deposition on the Metals, were characterized by ultraviolet-visible spectroscopy, X-ray powder diffraction, resonance Raman scattering, transmission electron microscopy (TEM), and electron diffraction. Afterward, the nanocrystal films were characterized by resonance Raman scattering, Rutherford back scattering (RBS), contact angle measurements, and TEM. All techniques indicate the presence of quantum confined clusters on the Metal Surfaces with a coverage of approximately 0.5 monolayers. These samples represent the first step toward synthesis of an organized assembly of clusters as well as allow the first application of electron spectroscopies to be completed on this type of cluster. As an example of this, the first X-ray photoelectron spectra of semiconductor nanocrystals are presented. 51 refs., 17 figs.
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Semiconductor Nanocrystals Covalently Bound to Metal Surfaces with Self-Assembled Monolayers
Journal of the American Chemical Society, 1992Co-Authors: Vicki L. Colvin, A. N. Goldstein, Armand P AlivisatosAbstract:A method is described for attaching semiconductor nanocrystals to Metal Surfaces using self-assembled difunctional organic monolayers as bridge compounds. Three different techniques are presented. Two rely on the formation of self-assembled monolayers on gold and aluminum in which the exposed tail groups are thiols. When exposed to heptane solutions of cadmium-rich nanocrystals, these free thiols bind the cadmium and anchor it to the surface. The third technique attaches nanocrystals already coated with carboxylic acids to freshly cleaned aluminum. The nanocrystals, before deposition on the Metals, were characterized by ultraviolet-visible spectroscopy, X-ray powder diffraction, resonance Raman scattering, transmission electron microscopy (TEM), and electron diffraction. Afterward, the nanocrystal films were characterized by resonance Raman scattering, Rutherford back scattering (RBS), contact angle measurements, and TEM. All techniques indicate the presence of quantum confined clusters on the Metal Surfaces with a coverage of approximately 0.5 monolayers. These samples represent the first step toward synthesis of an organized assembly of clusters as well as allow the first application of electron spectroscopies to be completed on this type of cluster. As an example of this, the first X-ray photoelectron spectra of semiconductor nanocrystals are presented. © 1992, American Chemical Society. All rights reserved.
A Hodgson - One of the best experts on this subject based on the ideXlab platform.
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water adsorption and the wetting of Metal Surfaces
Surface Science Reports, 2009Co-Authors: A HodgsonAbstract:Abstract Water adsorption at Metal Surfaces is governed by a subtle balance between water–water hydrogen bonding and water–Metal interactions, which together determine the stability of the water structures formed. This review describes recent experimental and theoretical studies of water and OH/water coadsorption on well-defined single crystal Metal Surfaces, systems that have seen an upsurge in interest as new results modify our picture of how water adsorbs on Metal Surfaces. These results reveal that the simple, conventional ice ‘bilayer’ description of water adsorption, in which water is only marginally distorted from its bulk ice arrangement, is inadequate to describe wetting. Instead, optimisation of the water–Metal interaction distorts the local hydrogen bonding geometry of water monolayers significantly from that of bulk ice, with consequent effects on the lateral size and geometry of ice clusters, on the structure of water monolayers and on the wetting of first layer water and growth of ice multilayers. Here we compare adsorption across different Metal Surfaces, review evidence for the formation of mixed OH/H 2 O co-adsorption structures and highlight issues that remain uncertain.
Geert Brocks - One of the best experts on this subject based on the ideXlab platform.
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work functions of self assembled monolayers on Metal Surfaces by first principles calculations
Physical Review B, 2006Co-Authors: P C Rusu, Geert BrocksAbstract:Using first-principles calculations we show that the work function of noble Metals can be decreased or increased by up to 2 eV upon the adsorption of self-assembled monolayers of organic molecules. We identify the contributions to these changes for several (fluorinated) thiolate molecules adsorbed on Ag(111), Au(111), and Pt(111) Surfaces. The work function of the clean Metal Surfaces increases in this order, but adsorption of the monolayers reverses the order completely. Bonds between the thiolate molecules and the Metal Surfaces generate an interface dipole, whose size is a function of the Metal, but it is relatively independent of the molecules. The molecular and bond dipoles can then be added to determine the overall work function
Sheng Meng - One of the best experts on this subject based on the ideXlab platform.
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water adsorption on Metal Surfaces a general picture from density functional theory studies
Physical Review B, 2004Co-Authors: Sheng Meng, Enge WangAbstract:We present a density functional theory study of water adsorption on Metal Surfaces. Prototype water structures including monomers, clusters, one-dimensional chains, and overlayers have been investigated in detail on a model system-a Pt(111) surface. The structure, energetics, and vibrational spectra are all obtained and compared with available experimental data. This study is further extended to other Metal Surfaces including Ru(0001), Rh(111), Pd(111), and Au(111), where adsorption of monomers and bilayers has been investigated. From these studies, a general picture has emerged regarding the water-surface interaction, the interwater hydrogen bonding, and the wetting order of the Metal Surfaces. The water-surface interaction is dominated by the lone pair-d band coupling through the surface states. It is rather localized in the contacting layer. A simultaneous enhancement of hydrogen bonding is generally observed in many adsorbed structures. Some special issues such as the partial dissociation of water on Ru(0001) and in the RT39 bilayer phase, the H-up and H-down conversion, and the quantum-mechanical motions of H atoms are also discussed.
