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An analysis of LEED data from the Ag(111) surface at room temperature and 5° ? Θ ? 16°, φ = 12° has been carried out in order to test three different model potentials for the exchange and correlation part of the one-electron LEED potential. Clean Au(111) surfaces have been grown on Ag(111) at room temperature at a deposition rate of 0.15 Å s?1. Similar method of calculation and potentials have been employed for the Au overlay er on Ag(111). After the deposition of ? 2.5 monolayers of Au/Ag(111) the growth of Au can proceed in two different ways. One of them matches satisfactorily with the theoretical calculation for the Au(111) overlayer on Ag(111) following the fcc sequence. The other seems to be concerned with the diffusion of Ag during the Au growth. Similar curves have been obtained during the diffusion of Ag through 350 Å of Au(111). 相似文献
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H. Klein W. Blanc R. Pierrisnard C. Fauquet Ph. Dumas 《The European Physical Journal B - Condensed Matter and Complex Systems》2000,14(2):371-376
We report here a preparation for thin gold films on mica substrates. We have investigated the influence of the substrate temperature
and the evaporation rate on the morphology of the films. After careful outgasing of the substrate, 100 nm of Au is evaporated
onto the mica surface maintained at high temperature. After slow cooling, ex situ characterizations are performed using AFM and STM. For our purposes, the best compromise between roughness and grain size
is found to occur for an evaporation rate of 2 ?s-1 onto a mica substrate maintained at 460 C. We have used these substrates for STM and AFM study of decanethiol self-assembled monolayers (SAMs). We present results
for gold samples immersed for a few seconds in decanethiol solutions, revealing an incomplete organization of the films. The
organization process is discussed through comparison between AFM and STM data recorded on the SAMs. Then we present molecular
resolution STM pictures of ordered SAMs for longer immersion times.
Received 25 May 1999 相似文献
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J. C. Walker H. Tang M. D. Wieczorek D. J. Keavney D. F. Storm C. J. Gutierrez Z. Q. Qiu 《Hyperfine Interactions》1992,68(1-4):271-274
A comparison of the magnetic and structural properties and growth characteristics between Fe(110)/Ag(111) and Fe(100)/Ag(100)
multilayers is presented. The two types of multilayers were made of the same constituent materials but with different oricutations,
allowing us to examine the interesting interplay between structure and magnetism. We found fundamentally different magnetic
properties including magnetocrystalline anisotropy and surface/interface and thin film magnetism for the two types of multilayers,
and their origins were discussed.
Presently at the Naval Research Laboratory.
Presently at Argonne National Laboratory. 相似文献
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《中国物理 B》2015,(4)
The strain distributions of Au/Ag and Ag/Au nanoparticles confined in the Al2O3 matrix with different core sizes are investigated by using the finite element method, respectively. The simulation results clearly indicate that the compressive strains exerted on the Au/Ag and Ag/Au nanoparticles can be induced by the Al2O3 matrix. Moreover, it can be found that the strain gradient existing in a Au/Ag nanoparticle is much larger than that in a Ag/Au nanoparticle, which could be due to the larger Young's modulus of Au than that of Ag. With the core size increasing, the strain gradient existing in the Au/Ag nanoparticle becomes larger, while the strain gradient existing in the Ag/Au nanoparticle keeps constant. These different strain distributions may have significant influences on the structures and morphologies of the Au/Ag and Ag/Au nanoparticles, leading to the different physical properties for potential applications. 相似文献
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The intermixed region at the Si(111)/Au interface has been studied with ultraviolet photoemission (hν=21.2 eV and hν=10.2 eV) as a function of thermal treatment of the junction (from RT up to 550°C). At increasing temperatures a chemically driven intermixing takes place. The results depend markedly on the temperature up to ? 350 – 400°C. At higher temperatures a stable interface phase which behaves as a small gap semicondductor has been formed. 相似文献
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The nature of sulfate-Ag(111) and sulfate-Au(111) surface bonding has been investigated at the SCF + MP2 level of theory. Convergence of binding energy with cluster size is investigated and, unlike neutral adsorbates, large clusters are required in order to obtain reliable binding energies. In the most stable adsorption mode, sulfate binds to the surface via three oxygen atoms (C3v symmetry) with a binding energy of 159.3 kcal/mol on Ag(111) and 143.9 kcal/mol on Au(111). The geometry of adsorbed sulfate was optimized at the SCF level. While the bond length between sulfur and the oxygens coordinated to the surface increases, the sulfur-uncoordinated oxygen bond length decreases. This weakening and strengthening of the bonds, respectively, is consistent with bond order conservation in adsorbates on metal surfaces. Although a charge transfer of 0.4 electrons towards the metal is observed, the adsorbate remains very much sulfate-like. The molecular orbital analysis indicates that there is also some charge back-donation towards unoccupied orbitals of sulfate. This results in an increased electron density around sulfur as revealed in the electron density difference maps. Analysis of the Laplacian of the charge density of free sulfate provides a suitable framework to understand the nature of the different charge transfer processes and allows us to establish some similarities with the CO- and SO2-metal bondings. 相似文献
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It is well known that the Ag/Ag(111) epitaxial system grows three dimensionally because of the existence of a relatively high excess diffusion barrier, DeltaE(s) = 0.13 eV, at the step edges. Several experimental methods have been developed to measure the step edge barrier in this system over a wide coverage range. The probability for an atom to move from a higher to a lower layer depends on both the barrier and the prefactor, so it is important to test whether the prefactors for hopping over a step, nu(s), and for hopping on a terrace, nu(t), are different. We present the results from several experiments on Ag/Ag(111) to conclude that nu(s)/nu(t) = 10(2.0+/-0. 3). 相似文献
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We employ angle-resolved photoemission to study the electronic structure of atomically uniform films of Ag grown on Ge(111). A new kind of quantum well state is observed near a specific emission direction away from the surface normal. In contrast with the usual quantum well state arising from electron confinement by specular reflections at the surface and interface of the film, the new kind involves retroreflections, or umklapp reflections, at the interface. It requires four reflections, instead of the usual two reflections, to complete a coherent interference path. 相似文献
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Ling WL de la Figuera J Bartelt NC Hwang RQ Schmid AK Thayer GE Hamilton JC 《Physical review letters》2004,92(11):116102
We report an experimental (scanning tunneling microscopy) and theoretical (embedded atom method) study of a heterophase interface reconstruction between Ag(111) and Ru(0001). Despite the large 7% mismatch, the second layer of Ag from the Ru exhibits a hexagonal structure with Ag bulk spacing, providing a close match to bulk Ag. The first layer of Ag (next to Ru) is reconstructed in a highly symmetrical and regular structure containing monolayer long threading dislocations. We argue that this structure may generally occur to relieve strain in a certain class of heterophase interfaces. 相似文献