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Chemisorption

About: Chemisorption is a research topic. Over the lifetime, 16298 publications have been published within this topic receiving 554989 citations.


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TL;DR: In this article, two models have been studied as alternative representations of the admolecule surface interactions in layers formed by the self-assembly of alkyl thiol [SH(CH2)15CH3] molecules onto a gold substrate.
Abstract: Molecular dynamics simulations have been used to study the structure and dynamics of monolayers of long‐chain molecules on a metallic substrate. The system consisted of 90 molecules held at a fixed surface density and periodically replicated in the plane of the surface. Two models have been studied as alternative representations of the admolecule–surface interactions in layers formed by the self‐assembly of alkyl thiol [SH(CH2)15CH3] molecules onto a gold substrate. The principal difference between the two models is that in one, the S–C bond is required to lie nearly parallel to the substrate surface. After lengthy equilibration at room temperature, both models yield monolayers in which the chains are aligned and tilted with respect to the surface normal. Although the tilt angle is different for the two models, the thickness of the monolayers is the same and the influence of the ‘‘modified‐headgroup’’ on the detailed structure of the film is confined to the region closest to the metal surface. There are s...

377 citations

Journal ArticleDOI
TL;DR: In this article, the dynamics of activated dissociative chemisorption of CH4 on Ni(111) were studied by molecular beam techniques coupled with high-resolution electron energy loss spectroscopy.
Abstract: The dynamics of the activated dissociative chemisorption of CH4 on Ni(111) are studied by molecular beam techniques coupled with high‐resolution electron energy loss spectroscopy. The probability of the dissociative chemisorption of CH4 increases exponentially with the normal component of the incident molecule’s translational energy and with vibrational excitation. The dissociative chemisorption probability of CD4 exhibits the same trends with a large kinetic isotope effect. High‐resolution electron energy loss spectroscopy identifies the nascent products of the dissociative chemisorption event as an adsorbed methyl radical and a hydrogen atom. These results, which have shown that there is a barrier to the dissociative chemisorption, are interpreted in terms of a deformation model for the role of translational and vibrational energy in promoting dissociative chemisorption. The barrier likely arises largely from the energy required to deform the molecule sufficiently to allow a strong attractive interaction between the carbon and the Ni surface atoms. Tunneling is suggested as the final process in the C–H bond cleavage. The presence of this barrier to dissociative chemisorption presents a plausible explanation for the pressure gap in heterogeneous catalysis.

375 citations

Journal ArticleDOI
TL;DR: In this paper, it was shown that the separation in energy between the 4σ and 1π peaks of chemisorbed CO varies systematically with the position of the adsorbent in the Periodic Table.

371 citations

Journal ArticleDOI
TL;DR: Results, in conjunction with previous literature reports, indicate that as-prepared nanocrystal surfaces are terminated by X-type binding of octadecylphosphonate moieties to a layer of excess cadmium ions.
Abstract: The surface chemistry of cadmium selenide nanocrystals, prepared from tri-n-octylphosphine selenide and cadmium octadecylphosphonate in tri-n-octylphosphine oxide, was studied with 1H and {1H}31P NMR spectroscopy as well as ESI-MS and XPS. The identity of the surface ligands was inferred from reaction of nanocrystals with Me3Si−X (X = −S−SiMe3, −Se−SiMe3, −Cl and −S−(CH2CH2O)4OCH3)) and unambiguous assignment of the organic byproducts, O,O′-bis(trimethylsilyl)octadecylphosphonic acid ester and O,O′-bis(trimethylsilyl)ocatdecylphosphonic acid anhydride ester. Nanocrystals isolated from these reactions have undergone exchange of the octadecylphosphonate ligands for −X as was shown by 1H NMR (X = −S−(CH2CH2O)4OCH3) and XPS (X = −Cl). Addition of free thiols to as prepared nanocrystals results in binding of the thiol to the particle surface and quenching of the nanocrystal fluorescence. Isolation of the thiol-ligated nanocrystals shows this chemisorption proceeds without displacement of the octadecylphosphona...

370 citations

Journal ArticleDOI
TL;DR: In this article, the atom-jellium model of chemisorption was used to study the properties of an atom bonded to the surface of a simple metal, including the electron-density distribution, the state density, the dipole moment, and the heat of adsorption.
Abstract: We use the atom-jellium model of chemisorption to study the properties of an atom bonded to the surface of a simple metal. Beyond the jellium simulation of the metal substrate and the Kohn-Sham local-density description of exchange and correlation, we make no significant approximations: our solutions are parameter free, wave mechanical, and fully self-consistent. We solve this model for a set of adatoms exhibiting a variety of chemical behaviors. Properties studied include the electron-density distribution, the state density, the dipole moment, and the heat of adsorption. We discuss also the reintroduction of the discrete lattice structure of the substrate using perturbation theory.

366 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
2023567
20221,044
2021538
2020424
2019458
2018350