Structural studies of alkali metal adsorption and coadsorption on metal surfaces
TL;DR: A review of recent studies of adsorption and coadsorption using specifically structural techniques can be found in this paper, with the intention of highlighting recent developments, providing a useful reference base to the community, and drawing attention to some unifying concepts.
About: This article is published in Surface Science Reports.The article was published on 1996-01-01. It has received 273 citations till now. The article focuses on the topics: Adsorption.
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TL;DR: A review of the fundamental interactions of water with solid surfaces can be found in this paper, where the authors assimilated the results of the TM review with those covered by the authors to provide a current picture of water interactions on solid surfaces, such as how water adsorbs, what are the chemical and electrostatic forces that constitute the adsorbed layer, how is water thermally or non-thermally activated and how do coadsorbates influence these properties of water.
2,022 citations
TL;DR: The long-range ordering as well as the scanning tunneling microscopy appearance of single Au atoms on a 3 monolayer thin MgO film can be explained by partial charge transfer from the substrate to Au atoms as predicted recently by density functional theory calculations.
Abstract: The identification of concepts which allow understanding and subsequently tuning the catalytic properties of heterogeneous catalysts is still one of the key issues of research in catalysis. A variety of different strategies have been put forward over the last decades in the effort to compass and establish a rational design of heterogeneous catalysts [1]. Most of these strategies are based on structure reactivity relationships, taking different aspects of the exceedingly complex systems into account. To this end model systems using metal particles supported on well ordered thin oxide films of appropriate thickness, which allow investigations with the rigor of modern surface science while grasping essential aspects of the complexity of real systems, have proven to give valuable insight into the details of geometric and electronic structure, as well as adsorption and reaction properties [2–6]. It has been recognized that the thickness of the oxide films, as they are grown on metal substrates, may be used as a design principle to create materials of potential in catalysis. A concept to control the catalytic activity of a dispersed metal by the thickness of an insulating oxide layer was introduced some 20 years ago by Cogen et al. using silica layers covering Pt [7]. In this case the catalytic performance for dehydrogenation of cycloalkenes depends significantly on the thickness of the silica films, which was explained by the decreasing transport of hydrogen atoms produced at the Pt surface through the silica film. The main experimental challenge, however, is to provide undisputable prove for the proposed mechanisms which is usually hampered either by the complexity of the samples investigated and/or the lack of appropriate methodology to exclude interference with alternative mechanisms. Having ultimate control, as available today, over the thickness and structure of the oxide films, these properties may be used to control the charge state and, thus, the catalytic properties of a metal deposited onto them, an idea related to those proposed by Cabrera and
291 citations
TL;DR: In this article, the chemical reactions of organic molecules and fragments on solid surfaces, mainly on single crystals of metals but also on crystals of metal oxides, carbides, nitrides, phosphides, sulfides and semiconductors as well as on more complex models such as bimetallics, alloys, and supported particles, are reviewed.
240 citations
TL;DR: This work presents a probabilistic simulation of the response of the immune system to various types of collisions and shows clear patterns of response to different types of materials.
Abstract: We gratefully acknowledge support by the Department of Education of the Government of the Basque Country, Spanish MCyT (Grant No. MAT2001-0946), and the European Community 6th Network of Excellence NANOQUANTA (NMP4-CT-2004-500198).
219 citations
TL;DR: In this article, a survey of state-of-the-art scanning tunneling microscopy (STM) experiments aiming at an investigation of surface properties of oxide materials as well as their interaction with individual adatoms, molecules and metal particles is presented.
205 citations
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23,110 citations
Book•
01 Jan 1953
TL;DR: In this paper, the Hartree-Fock Approximation of many-body techniques and the Electron Gas Polarons and Electron-phonon Interaction are discussed.
Abstract: Mathematical Introduction Acoustic Phonons Plasmons, Optical Phonons, and Polarization Waves Magnons Fermion Fields and the Hartree-Fock Approximation Many-body Techniques and the Electron Gas Polarons and the Electron-phonon Interaction Superconductivity Bloch Functions - General Properties Brillouin Zones and Crystal Symmetry Dynamics of Electrons in a Magnetic Field: de Haas-van Alphen Effect and Cyclotron Resonance Magnetoresistance Calculation of Energy Bands and Fermi Surfaces Semiconductor Crystals I: Energy Bands, Cyclotron Resonance, and Impurity States Semiconductor Crystals II: Optical Absorption and Excitons Electrodynamics of Metals Acoustic Attenuation in Metals Theory of Alloys Correlation Functions and Neutron Diffraction by Crystals Recoilless Emission Green's Functions - Application to Solid State Physics Appendix: Perturbation Theory and the Electron Gas Index.
21,954 citations
TL;DR: In this article, a new definition of order called topological order is proposed for two-dimensional systems in which no long-range order of the conventional type exists, and the possibility of a phase transition characterized by a change in the response of the system to an external perturbation is discussed in the context of a mean field type of approximation.
Abstract: A new definition of order called topological order is proposed for two-dimensional systems in which no long-range order of the conventional type exists. The possibility of a phase transition characterized by a change in the response of the system to an external perturbation is discussed in the context of a mean field type of approximation. The critical behaviour found in this model displays very weak singularities. The application of these ideas to the xy model of magnetism, the solid-liquid transition, and the neutral superfluid are discussed. This type of phase transition cannot occur in a superconductor nor in a Heisenberg ferromagnet.
6,371 citations
TL;DR: The interesting result of the studied systems is that the difference in bond strengths between the ``normal'' and substitutional geometries is sufficiently large to kick out a surface Al atom.
Abstract: We present total-energy, force, and electronic-structure calculations for Na and K adsorbed in various geometries on an Al(111) surface. The calculations apply density-functional theory together with the local-density approximation and the ab initio pseudopotential formalism. Two adsorbate meshes, namely, (\ensuremath{\surd}3 \ifmmode\times\else\texttimes\fi{} \ensuremath{\surd}3 )R30\ifmmode^\circ\else\textdegree\fi{} and (2\ifmmode\times\else\texttimes\fi{}2), are considered and for each of them the geometry of the adlayer relative to the substrate is varied over a wide range of possibilities. By total-energy minimization we determine stable and metastable geometries. For Na we find for both adsorbate meshes that the ordering of the calculated binding energies per adatom is such that the substitutional geometry, where each Na atom replaces a surface Al atom, is most favorable and the on-top position is most unfavorable. The (\ensuremath{\surd}3 \ifmmode\times\else\texttimes\fi{} \ensuremath{\surd}3 )R30\ifmmode^\circ\else\textdegree\fi{} structure has a lower energy than the (2\ifmmode\times\else\texttimes\fi{}2) structure. This is shown to be a substrate effect and not an effect of the adsorbate-adsorbate interaction. In contrast to the results for Na, we find for the (\ensuremath{\surd}3 \ifmmode\times\else\texttimes\fi{} \ensuremath{\surd}3 )R30\ifmmode^\circ\else\textdegree\fi{} K adsorption that the calculated adsorption energies for the on-top, threefold hollow, and substitutional sites are equal within the accuracy of our calculation, which is \ifmmode\pm\else\textpm\fi{}0.03 eV. The similarity of the energies of the on-surface adsorption sites is explained as a consequence of the bigger size of K which implies that the adatom experiences a rather small substrate electron-density corrugation. Therefore for potassium the on-top and hollow sites are close in energy already for the unrelaxed Al(111) substrate. Because the relaxation energy of the on-top site is larger than that of the threefold hollow site both sites receive practically the same adsorption energy. The unexpected possibility of surface-substitutional sites is explained as a consequence of the ionic nature of the bonding which, at higher coverages, can develop strongest when the adatom can dive into the substrate as deep as possible. The interesting result of the studied systems is that the difference in bond strengths between the ``normal'' and substitutional geometries is sufficiently large to kick out a surface Al atom.
2,124 citations
TL;DR: In this paper, a theory of dislocation-mediated melting in two dimensions is described in detail, with an emphasis on results for triangular lattices on both smooth and periodic substrates, and the behavior of the specific heat, structure factor, and various elastic constants near these transitions is worked out.
Abstract: A theory of dislocation-mediated melting in two dimensions is described in detail, with an emphasis on results for triangular lattices on both smooth and periodic substrates. The transition from solid to liquid on a smooth substrate takes place in two steps with increasing temperatures. Dissociation of dislocation pairs first drives a transition out of a low-temperature solid phase, with algebraic decay of translational order and long-range orientational order. This transition is into a "liquid-crystal" phase characterized by exponential decay of translational order, but power-law decay of sixfold orientational order. Dissociation of disclination pairs at a higher temperature then produces an isotropic fluid. The behavior of the specific heat, structure factor, and various elastic constants near these transitions is worked out. We also discuss the applicability of our results to melting on a periodic substrate. Dislocation unbinding should describe melting of a "floating" (and, in general, incommensurate) adsorbate solid into a high-temperature fluid phase. The orientation bias imposed by the substrate can alter or eliminate the disclination-unbinding transition, however. Transitions from a floating solid into a low-temperature registered or partially registered phase can also be mapped onto the dislocation-unbinding transition, but only at certain special values of the coverage. Substrate reciprocallattice vectors play the role of Burger's vectors in this case.
1,476 citations