Ultrathin films of NaCl on Cu(111): a LEED and dynamic force microscopy study

Bennewitz, Roland; Barwich, V.; Bammerlin, M.; Loppacher, Christian; Guggisberg, Martin; Baratoff, A.; Meyer, Ernst; Güntherodt, H.‐J.

doi:10.1016/s0039-6028(99)00586-5

Cited by 111 publications

(93 citation statements)

References 14 publications

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“…Previous investigations on the growth of ionic layers on flat metal surfaces [8,11,12] show that the here-observed behavior is unique. Hebenstreit et al, for instance, investigated the room temperature growth of NaCl on Al(111) and Al(100) [the misfit between Al(100) and NaCl is ,2%].…”

Section: (Received 7 September 2000)supporting

confidence: 49%

“…This model has to explain (1) the binding sites of NaCl with respect to the Cu(311) surface, (2) the difference in binding strength for NaCl on Cu(311) and on flat metal surfaces [8,11,12], and (3) the comparably large misfit of 6% perpendicular to the Cu rows -common models as the picture of image charges fail to explain these features without further complicated assumptions. We therefore propose a new model which is based on an inherent attribute of regularly stepped metal surfaces, namely charge modulation due to the Smoluchowski effect.…”

Section: (Received 7 September 2000)mentioning

confidence: 99%

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Ionic Films on Vicinal Metal Surfaces: Enhanced Binding due to Charge Modulation

et al. 2001

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NaCl films on Cu(311) exhibit a remarkably strong and localized binding between adlayer and substrate. The binding sites of the ions in the NaCl film with respect to the Cu surface are determined from atomically resolved scanning tunneling microscopy images. A new model is proposed in which the binding mechanism is controlled by the charge modulation of a regularly stepped surface due to the Smoluchowski effect. This model can be extended to explain the growth of ionic adlayers on regularly stepped and kinked metal surfaces in general. DOI: 10.1103/PhysRevLett.86.252 PACS numbers: 68.55. -a There is a long standing interest in the growth of ultrathin insulating films on conductive substrates due to their importance in catalysis and device applications. Additionally, the use of thin films circumvents the problem of surface charging and thereby allows one to investigate insulator surfaces by standard surface analysis techniques. To grow thin insulating films different techniques have been developed, depending on the selected substrate and deposit. In the important field of metal oxides, for example, both components of the film are introduced separately and the film can be grown either by metal deposition and subsequent oxidation, or by simultaneous oxidation during growth [1,2]. In the case of alkali halides the film is grown by direct deposition of the complete alkali halide molecule. While the chemical reactivity of insulators varies, a common feature is their polar nature. In the case of nonreactive alkali halides surface binding is dominated by Coulomb interactions between ionic and/or image charges [3]. Therefore, substrates with polar character will have a strong influence on the growth characteristics. In this respect vicinal surfaces are of utmost interest [4] since charge smoothing at step edges due to the Smoluchowski effect and the resulting electrostatic dipole at steps produces a charge-modulated surface [5]. Since regularly stepped or regularly kinked surfaces can be prepared in multiple orientations, the lateral periodicity of this kind of charge modulation can be varied with great flexibility.In this Letter, we show that the concept of the chargemodulated substrate surface is a powerful tool to control epitaxial 2D growth of ionic insulator films with high perfection. As an exemplary case, we have studied the epitaxial growth of NaCl on Cu(311) by low temperature scanning tunneling microscopy (LT-STM). From a series of detailed STM experiments we determine the location of the chlorine ions to be on top of the intrinsic step edges of the Cu(311) surface. This observation can be explained by a very general model, which takes into account the charge modulation of a stepped surface due to the Smoluchowski effect. The model can be also extended to the growth behavior observed on regularly kinked surfaces as shown in the case of Cu(531).Our experiments were performed with a LT-STM [6] operated at 13 K. We used a chemomechanically polished Cu(311) single crystal which was cleaned by Ne 1 sputtering an...

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Section: (Received 7 September 2000)supporting

confidence: 49%

Section: (Received 7 September 2000)mentioning

confidence: 99%

Ionic Films on Vicinal Metal Surfaces: Enhanced Binding due to Charge Modulation

et al. 2001

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“…18 In our model study, we have taken the geometry of the adsorbed layers from previous theoretical calculations 33 and experimental measurements. 31 The lattice constant of the two-dimensional NaCl layer, l = 5.47Å, has been taken from the LEED experimental results of Ref. 31.…”

Section: Methods and Computational Detailsmentioning

confidence: 99%

Theoretical study of the electronic excited states in ultrathin ionic layers supported on metal surfaces: NaCl/Cu(111)

2011

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We present a theoretical study of the electronic excited states in ultrathin ionic layers supported on metal surfaces. We have studied 1, 2, 3, and 4 monolayers of NaCl on a Cu(111) surface. Energies, lifetimes, and associated wave functions of the excited states have been obtained with a joint, model potential-wave packet propagation approach. The excited state with the lowest energy has the character of an image potential state repelled from the surface by the NaCl layer. The next two states present a mixed character of image potential states and NaCl layer states corresponding to the quantization of the conduction band in the finite-size layer. We discuss the role of the layer thickness in decoupling these states from the metal surface and how it affects their lifetime.

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“…Specifically, high-quality atomic resolution was achieved on NaCl (001) films on copper substrates (Bennewitz et al, 1999a. Growth modes, orientation, and lattice constants of ultrathin films were revealed (Bennewitz et al, 1999b), and atomic resolution at step edges was demonstrated (Bennewitz et al, 1999a). Also, the prevalence of low-coordinated sites, such as steps, corners, and kinks on these thin films makes them of special interest for catalytic studies, and NC-SFM offers the possibility of imaging these features in atomic resolution.…”

Section: Nacl Thin Films On Cu(111) Surfacementioning

confidence: 99%

Theories of scanning probe microscopes at the atomic scale

2003

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Significant progress has been made both in experimentation and in theoretical modeling of scanning probe microscopy. The theoretical models used to analyze and interpret experimental scanning probe microscope (SPM) images and spectroscopic data now provide information not only about the surface, but also the probe tip and physical changes occurring during the scanning process. The aim of this review is to discuss and compare the present status of computational modeling of two of the most popular SPM methods-scanning tunneling microscopy and scanning force microscopy-in conjunction with their applications to studies of surface structure and properties with atomic resolution. In the context of these atomic-scale applications, for the scanning force microscope (SFM), this review focuses primarily on recent noncontact SFM (NC-SFM) results. After a brief introduction to the experimental techniques and the main factors determining image formation, the authors consider the theoretical models developed for the scanning tunneling microscope (STM) and the SFM. Both techniques are treated from the same general perspective of a sharp tip interacting with the surface-the only difference being that the control parameter in the STM is the tunneling current and in the SFM it is the force. The existing methods for calculating STM and SFM images are described and illustrated using numerous examples, primarily from the authors' own simulations, but also from the literature. Theoretical and practical aspects of the techniques applied in STM and SFM modeling are compared. Finally, the authors discuss modeling as it relates to SPM applications in studying surface properties, such as adsorption, point defects, spin manipulation, and phonon excitation. CONTENTS

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Ultrathin films of NaCl on Cu(111): a LEED and dynamic force microscopy study

Cited by 111 publications

References 14 publications

Ionic Films on Vicinal Metal Surfaces: Enhanced Binding due to Charge Modulation

Ionic Films on Vicinal Metal Surfaces: Enhanced Binding due to Charge Modulation

Theoretical study of the electronic excited states in ultrathin ionic layers supported on metal surfaces: NaCl/Cu(111)

Theories of scanning probe microscopes at the atomic scale

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