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| 2. |
- Crispin, Xavier, et al.
(författare)
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Chemisorption of acrylonitrile on the Cu(100) surface: A local density functional study
- 1999
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Ingår i: Journal of Chemical Physics. - : American Institute of Physics (AIP). - 0021-9606 .- 1089-7690. ; 111:7, s. 3237-3251
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Tidskriftsartikel (refereegranskat)abstract
- The possibility of chemically grafting polyacrylonitrile onto transition metal electrodes via electropolymerization leads to promising applications in the fields of corrosion protection or metal surface functionalization. The initial step of the electrografting mechanism is the adsorption of the acrylonitrile monomer on the metal surface from solution. Here, we investigate theoretically this adsorption process on the copper (100) surface; Density Functional Theory is used in the Local Spin Density approximation to describe the electronic and structural properties of acrylonitrile adsorbed on copper clusters. The chemisorption of acrylonitrile on the copper surface is confirmed experimentally via X-Ray Photoelectron Spectroscopy. The thermodynamic characteristics of the adsorption process are also studied via statistical mechanics. Finally, determining the influence of the copper cluster size on the adsorption of acrylonitrile allows to extrapolate the properties of the acrylonitrile/Cu(100) surface from those of acrylonitrile/copper clusters. (C) 1999 American Institute of Physics. [S0021-9606(99)70231-X].
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| 3. |
- Crispin, Xavier, et al.
(författare)
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Understanding the initial stages of polymer grafting on metals : A photoelectron spectroscopy study of acrylonitrile adsorption on transition metal surfaces
- 2001
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Ingår i: Journal of Electron Spectroscopy and Related Phenomena. - 0368-2048 .- 1873-2526. ; 121:1-3, s. 57-74
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Tidskriftsartikel (refereegranskat)abstract
- X-ray and UV photoelectron spectroscopies show that acrylonitrile is chemisorbed on iron, nickel and copper polycrystalline surfaces via the carbon and nitrogen atoms. Depending on the conditions used, different adsorption geometries are found. The molecules can either be adsorbed flat on the surface and chemically bound by a (2pp)-(3d/4s) overlap via both the C=C double bond and the C=N nitrile group or they can be adsorbed perpendicular to the surface via a covalent interaction between the nitrogen lone pair and the 3d-4s levels of the metals. Analysis of the XPS data obtained on molecular mono-layers chemisorbed on metal surfaces emphasizes the importance of initial-state effects (charge transfer upon chemisorption, contribution of the metal surface dipole) and final-state effects (metal screening and polarization effect within the mono-layer). The correlation between the XPS and UPS data illustrates the importance of the metal surface dipole in understanding the workfunction changes upon molecular adsorption on metal surfaces. © 2001 Elsevier Science B.V. All rights reserved.
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| 4. |
- Vonau, F, et al.
(författare)
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Branched Substituents Generate Improved Supramolecular Ordering in Physisorbed Molecular Assemblies
- 2009
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Ingår i: JOURNAL OF PHYSICAL CHEMISTRY C. - : American Chemical Society (ACS). - 1932-7447 .- 1932-7455. ; 113:12, s. 4955-4959
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Tidskriftsartikel (refereegranskat)abstract
- We present an experimental study supported by molecular simulations of the influence of the shape of alkyl side groups on the interactions and self-organization of supramolecular assemblies, built from bis-ureasubstituted toluene molecules deposited on Au(111) surfaces. In particular, we demonstrate the crucial importance of the presence of branched alkyl groups (i.e., ethylhexyl) that allow two adjacent supramolecular polymers to arrange closer to each other, leading to the formation of molecular "zippers". Thus, steric constraints at the level of individual molecules can generate improved Ordering between neighboring supramolecular polymers interacting with a planar substrate.
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