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Search for "adsorbate" in Full Text gives 128 result(s) in Beilstein Journal of Nanotechnology.

Electronic and electrochemical doping of graphene by surface adsorbates

  • Hugo Pinto and
  • Alexander Markevich

Beilstein J. Nanotechnol. 2014, 5, 1842–1848, doi:10.3762/bjnano.5.195

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  • electrochemical doping. The electronic doping is a consequence of the direct charge transfer between graphene and an adsorbate. This requires a difference in electronic chemical potentials at an interface, which is determined by the relative positions of the graphene Fermi level and the highest occupied (HOMO
  • ) and lowest unoccupied (LUMO) molecular orbitals of an adsorbate. If the LUMO of the adsorbate lies lower in energy than the Fermi level of graphene, Figure 1a, electrons will flow from graphene to the adsorbate making graphene p-type-doped. Adsorbates with the HOMO lying above the graphene Fermi level
  • relative position of the highest occupied (HOMO) and lowest unoccupied (LUMO) molecular orbitals of an adsorbate to the Fermi level of graphene for a) p-type and b) n-type dopant. Conductivity as a function of the gate voltage (σ(Vg)) of graphene at different exposures to K. The shift of neutrality point
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Published 23 Oct 2014

Restructuring of an Ir(210) electrode surface by potential cycling

  • Khaled A. Soliman,
  • Dieter M. Kolb,
  • Ludwig A. Kibler and
  • Timo Jacob

Beilstein J. Nanotechnol. 2014, 5, 1349–1356, doi:10.3762/bjnano.5.148

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  • driven, it is hindered (and limited) by the kinetic barriers involved in the atom rearrangement at the surface [37]. Thus, not only a critical adsorbate (here oxygen) coverage is required but also appropriate activation, allowing the system to overcome the kinetic barriers in the process of facet
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Published 25 Aug 2014

Double layer effects in a model of proton discharge on charged electrodes

  • Johannes Wiebe and
  • Eckhard Spohr

Beilstein J. Nanotechnol. 2014, 5, 973–982, doi:10.3762/bjnano.5.111

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  • efficiency of the catalyst. In addition, platinum was deemed suitable because substantial simulation work has been done on this system before. Much work has been done in recent years by using mostly quantum mechanical density functional theory (DFT) to study adsorbate energetics and geometries on many
  • negatively charged electrode surfaces. Specifically, we studied four different systems: double layers with 1 or 2 adsorbed Cl− ions and one with a single adsorbed Na+ ion; in addition a reference system consisting of a pure water adsorbate layer was studied. In order to prevent desorption of the negatively
  • . Another alternative would have been to keep the position of the anions fixed. Once adsorbed, the Na+ ion, on the other hand, did never desorb from the surface but was free to diffuse within the adsorbate water layer. Hence, while the anions are specifically tethered to a site on the surface, the cation is
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Published 07 Jul 2014

Adsorption and oxidation of formaldehyde on a polycrystalline Pt film electrode: An in situ IR spectroscopy search for adsorbed reaction intermediates

  • Zenonas Jusys and
  • R. Jürgen Behm

Beilstein J. Nanotechnol. 2014, 5, 747–759, doi:10.3762/bjnano.5.87

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  • hydrogen in the methanol adsorbate on an emersed polycrystalline Pt electrode was suggested from electrochemical thermal desorption mass spectrometry (ECTDMS) measurements based on the detection of carbon monoxide, hydrogen and traces of carbon dioxide during thermal desorption [44]. In a series of recent
  • measurements using deuterium labeled formaldehyde. In addition, this also provides information on the nature of the adsorbate. The rates of the COad build-up were quantified and the kinetic H/D isotope effect in COad formation was determined as a function of the electrode potential and temperature. In the
  • these low potentials supports a mechanism where formaldehyde oxidation to formic acid proceeds via the hydrated form of formaldehyde (methylene glycol) and its interaction with the initially adsorbate-free electrode. At lower potentials, the electrode surface is largely blocked by Hupd, which inhibits
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Published 30 May 2014

The role of surface corrugation and tip oscillation in single-molecule manipulation with a non-contact atomic force microscope

  • Christian Wagner,
  • Norman Fournier,
  • F. Stefan Tautz and
  • Ruslan Temirov

Beilstein J. Nanotechnol. 2014, 5, 202–209, doi:10.3762/bjnano.5.22

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  • rapid development of scanning probe microscopy (SPM) techniques, investigations of adsorbate–surface interactions on a single-molecule level have become possible [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18]. Especially interesting is the possibility of probing the molecule–surface
  • made on 3,4,9,10-perylene-tetracarboxylic-dianhydride (PTCDA) molecules [6] (cf. inset of Figure 1a). This system is considered to be an archetypal case of a functional organic adsorbate [1]. PTCDA interacts with surfaces via two distinct functionalities: the π-conjugated perylene core and the
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Published 26 Feb 2014

Change of the work function of platinum electrodes induced by halide adsorption

  • Florian Gossenberger,
  • Tanglaw Roman,
  • Katrin Forster-Tonigold and
  • Axel Groß

Beilstein J. Nanotechnol. 2014, 5, 152–161, doi:10.3762/bjnano.5.15

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  • combination of charge transfer and polarization effects on the adsorbate layer. The results are contrasted to the adsorption of fluorine on calcium, a system in which a decrease in the work function is also observed despite a large charge transfer to the halogen adatom. Keywords: density functional theory
  • adsorption of iodine and chlorine on Cu(111) [9] by using periodic density functional theory (DFT) calculations. Whereas chlorine causes the expected increase of the work function upon adsorption of an electronegative adsorbate, iodine leads to a surprising decrease of the work function for coverages up to
  • approximately 0.4 ML. By analyzing the underlying electronic structure, we were able to show that this behavior can be explained through a combination of charge transfer and polarization effects of the adsorbate layer. We have now extended this previous study by considering the adsorption of fluorine, chlorine
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Published 10 Feb 2014

Core level binding energies of functionalized and defective graphene

  • Toma Susi,
  • Markus Kaukonen,
  • Paula Havu,
  • Mathias P. Ljungberg,
  • Paola Ayala and
  • Esko I. Kauppinen

Beilstein J. Nanotechnol. 2014, 5, 121–132, doi:10.3762/bjnano.5.12

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  • molecular models such as coronenes differs significantly from graphene, which can be an issue. A prominent recent example of the value of XPS for studying graphene is in chemical functionalization, in which the pristine structure is modified by a known covalent adsorbate or a substitution. Besides
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Published 03 Feb 2014

The role of oxygen and water on molybdenum nanoclusters for electro catalytic ammonia production

  • Jakob G. Howalt and
  • Tejs Vegge

Beilstein J. Nanotechnol. 2014, 5, 111–120, doi:10.3762/bjnano.5.11

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  • vacant bridge site. The free energies for oxygen absorption are shown in Table 1 for neutral bias and the potential needed for ammonia production, and listed together with the energies for nitrogen and hydrogen (from [2]). At neutral bias, oxygen is the preferred adsorbate with adsorption energies of
  • for all electrochemical reaction steps for ammonia production, see Figure 5, are zero or lower as in the previous example on the Mo13O9 nanocluster. In the discussion of the preferential reactions on the Mo13O9 and Mo13O6 nanoclusters, all possible adsorbateadsorbate interactions are not included due
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Published 31 Jan 2014

Adsorption of the ionic liquid [BMP][TFSA] on Au(111) and Ag(111): substrate effects on the structure formation investigated by STM

  • Benedikt Uhl,
  • Florian Buchner,
  • Dorothea Alwast,
  • Nadja Wagner and
  • R. Jürgen Behm

Beilstein J. Nanotechnol. 2013, 4, 903–918, doi:10.3762/bjnano.4.102

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  • 10.3762/bjnano.4.102 Abstract In order to resolve substrate effects on the adlayer structure and structure formation and on the substrate–adsorbate and adsorbateadsorbate interactions, we investigated the adsorption of thin films of the ionic liquid (IL) 1-butyl-1-methylpyrrolidinium-bis
  • (trifluoromethylsulfonyl)imide [BMP][TFSA] on the close-packed Ag(111) and Au(111) surfaces by scanning tunneling microscopy, under ultra high vacuum (UHV) conditions in the temperature range between about 100 K and 293 K. At room temperature, highly mobile 2D liquid adsorbate phases were observed on both surfaces. At low
  • contact with the surface at potentials between −0.4 and −2.2 V vs the ferrocene/ferrocenium (Fc/Fc+) redox couple [28]. Hence, the presence of the IL adsorbate alone is not sufficient to induce a restructuring of the substrate surface. The information derived from STM imaging can be combined with results
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Published 16 Dec 2013

Magnetic anisotropy of graphene quantum dots decorated with a ruthenium adatom

  • Igor Beljakov,
  • Velimir Meded,
  • Franz Symalla,
  • Karin Fink,
  • Sam Shallcross and
  • Wolfgang Wenzel

Beilstein J. Nanotechnol. 2013, 4, 441–445, doi:10.3762/bjnano.4.51

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  • close to the edge, while the opposite is true for the zigzag edge. Additionally, in-plane pinning of the magnetization direction perpendicular to the edge itself is observed for the first time. Keywords: adsorbate; grapheme; graphene quantum dot; magnetic anisotropy; transition metal; Introduction
  • atoms for the AGQDs, and 33 and 97 carbon atoms for the ZGQDs. Each of the points represents the spin moment and EIO for an adsorbate position of the Ru adatom. Evidently, the larger the Ru moment the greater the value attained for EIO. Specific absorbate positions (edge, apex) are indicated by the text
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Published 10 Jul 2013

Influence of the solvent on the stability of bis(terpyridine) structures on graphite

  • Daniela Künzel and
  • Axel Groß

Beilstein J. Nanotechnol. 2013, 4, 269–277, doi:10.3762/bjnano.4.29

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  • describe the interaction between adsorbate, substrate and solvent. It is true that the force fields in this package tend to overestimate BTP adsorption energies on graphite [12]. Still, trends in the stability of BTP stuctures on graphite as a function of the environment should still be reproduced. As a
  • structures was found. Thermodynamically, the stability of the adsorbate structures is governed by the free energy. Neglecting entropic effects, the free energy of adsorption can be expressed as [13][32] where Eads is the adsorption energy per molecule in a given structure and ρ is the density of molecules
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Published 22 Apr 2013

Electronic and transport properties of kinked graphene

  • Jesper Toft Rasmussen,
  • Tue Gunst,
  • Peter Bøggild,
  • Antti-Pekka Jauho and
  • Mads Brandbyge

Beilstein J. Nanotechnol. 2013, 4, 103–110, doi:10.3762/bjnano.4.12

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  • investigate the kink-line propagation reaction proposed by our results. To this end it is important to include a realistic description of the actual substrate. It is also interesting to consider other adsorbate species, possibly introducing doping of the pseudo-ribbons and electronic gating. Finally
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Published 15 Feb 2013

Plasmonics-based detection of H2 and CO: discrimination between reducing gases facilitated by material control

  • Gnanaprakash Dharmalingam,
  • Nicholas A. Joy,
  • Benjamin Grisafe and
  • Michael A. Carpenter

Beilstein J. Nanotechnol. 2012, 3, 712–721, doi:10.3762/bjnano.3.81

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  • , and particularly for plasmonics-based gas sensing. The extremely high sensitivity of the plasmon resonance peak to changes in the free-electron density of gold nanoparticles or a change in the dielectric function of the metal-oxide host material due to adsorbate reactions on surfaces makes this a
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Published 31 Oct 2012

Dimer/tetramer motifs determine amphiphilic hydrazine fibril structures on graphite

  • Loji K. Thomas,
  • Nadine Diek,
  • Uwe Beginn and
  • Michael Reichling

Beilstein J. Nanotechnol. 2012, 3, 658–666, doi:10.3762/bjnano.3.75

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  • electrical conductivity, atomic flatness, chemical inertness and here also for its hydrophobic nature. Hydrophilic substrates could hinder the self-assembling ability of the molecules by strongly interacting with their amide functionalities and forcing them to lay flat on the surface. To study adsorbate
  • strikingly close resemblance to molecular fibrils, the two species can be distinguished from each other. Care has been practised at all stages during STM imaging as well as analysis to establish the adsorbate origin of the reported structures clearly. The ambiguity can be excluded due to the capability of
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Published 19 Sep 2012

Focused electron beam induced deposition: A perspective

  • Michael Huth,
  • Fabrizio Porrati,
  • Christian Schwalb,
  • Marcel Winhold,
  • Roland Sachser,
  • Maja Dukic,
  • Jonathan Adams and
  • Georg Fantner

Beilstein J. Nanotechnol. 2012, 3, 597–619, doi:10.3762/bjnano.3.70

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  • surface coverage is assumed to be limited to one monolayer, such that the maximum fractional coverage n/nML is 1, where nML stands for the full area density of a complete precursor monolayer and n for the temporally and spatially dependent precursor adsorbate density. The fraction of surface sites that is
  • available for adsorption is therefore 1 − n/nML. The model also includes surface diffusion, with diffusion constant D, and an average residence time τ for the precursor molecules before desorption. It furthermore takes into account the electron-induced dissociation leading to a reduction of the adsorbate
  • depletion rate kd defined as and the depleted adsorbate density nd = sJ/kd. The initial adsorbate density n(t = 0) was set to the adsorbate density after long times nr in the absence of the dissociation term. It is defined by the replenishment rate kr given by via the relation nr = sJ/kr. The important
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Published 29 Aug 2012

Spontaneous dissociation of Co2(CO)8 and autocatalytic growth of Co on SiO2: A combined experimental and theoretical investigation

  • Kaliappan Muthukumar,
  • Harald O. Jeschke,
  • Roser Valentí,
  • Evgeniya Begun,
  • Johannes Schwenk,
  • Fabrizio Porrati and
  • Michael Huth

Beilstein J. Nanotechnol. 2012, 3, 546–555, doi:10.3762/bjnano.3.63

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  • ligand weakens (it elongates from 1.16 Å in the free molecule to 1.25 Å in the adsorbate) and the Co–C bond strengthens (it shortens from 1.95 Å in the free molecule to 1.66 Å in the adsorbate). Further, the bond angle (Co–C=O) in the bridging ligands changes from 140 to 174°. In addition, the surface Si
  • result of geometry optimization and are discussed in the text. Calculated Bader charges for Co2(CO)8 in units of electrons in the gas phase and for the adsorbate on SiO2 surfaces. The numbers in parenthesis identify the CO ligand as shown in Figure 5a and Figure 7. Values indicated by an asterisk
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Published 25 Jul 2012

Distribution of functional groups in periodic mesoporous organosilica materials studied by small-angle neutron scattering with in situ adsorption of nitrogen

  • Monir Sharifi,
  • Dirk Wallacher and
  • Michael Wark

Beilstein J. Nanotechnol. 2012, 3, 428–437, doi:10.3762/bjnano.3.49

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  • the chemical nature, i.e., the electron density for SAXS or the neutron scattering length density (SLD) for SANS, of the pore walls in relation to the adsorbed gas. Thus, already small changes at the interface between the host material (the adsorbent) and the adsorbate can be monitored directly [21
  • ]. The fact that scattering in SANS measurements takes place at the nucleus, renders it superior compared to SAXS. In SANS there are multiple possibilities in the choice of the adsorbate (e.g., nitrogen, hydrocarbons, water, benzene, etc.), allowing tailored contrast-matching experiments [21][22][23][24
  • is as well a very suitable adsorbate. Compared to those with H2O/D2O mixtures, adsorption experiments with N2 are easier to perform and, in particular, require less time to reach the thermodynamic adsorption equilibrium. Furthermore, pristine benzene-PMO was subsequently functionalized with SO3H
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Published 30 May 2012

Molecular-resolution imaging of pentacene on KCl(001)

  • Julia L. Neff,
  • Jan Götzen,
  • Enhui Li,
  • Michael Marz and
  • Regina Hoffmann-Vogel

Beilstein J. Nanotechnol. 2012, 3, 186–191, doi:10.3762/bjnano.3.20

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  • surfaces, molecular growth is usually governed by strong adsorbate–substrate interactions. However, for some applications in the field of thin-film electronic devices, insulating substrates are required in order to decouple the molecular structure from the substrate. On insulators the interaction of the
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Published 29 Feb 2012

STM study on the self-assembly of oligothiophene-based organic semiconductors

  • Elena Mena-Osteritz,
  • Marta Urdanpilleta,
  • Erwaa El-Hosseiny,
  • Berndt Koslowski,
  • Paul Ziemann and
  • Peter Bäuerle

Beilstein J. Nanotechnol. 2011, 2, 802–808, doi:10.3762/bjnano.2.88

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  • demonstrates a major contribution of intermolecular van der Waals and H-bonding interactions to the stabilization of the monolayer on the HOPG surface. Conformational changes of the H12TCOOH molecules at the domain boundaries of the adsorbate were shown for the first time for self-assembling oligothiophenes
  • : Quantum chemical model of the adsorbate, including the electron-density distribution of the HOMO and HOMO−1 for the dimer. STM image of H6TCOOH. Left: 70 × 70 nm2, U = −360 mV, I = 50 pA. Center: 20 × 20 nm2, U = −361 mV, I = 50 pA. Right: Theoretical model. The small black arrows emphasize the H-bonding
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Published 07 Dec 2011

An MCBJ case study: The influence of π-conjugation on the single-molecule conductance at a solid/liquid interface

  • Wenjing Hong,
  • Hennie Valkenier,
  • Gábor Mészáros,
  • David Zsolt Manrique,
  • Artem Mishchenko,
  • Alexander Putz,
  • Pavel Moreno García,
  • Colin J. Lambert,
  • Jan C. Hummelen and
  • Thomas Wandlowski

Beilstein J. Nanotechnol. 2011, 2, 699–713, doi:10.3762/bjnano.2.76

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  • AC. We note that the maximum in the adsorbate-free control experiment at around 0.9 nm (Figure 9D) results from tunneling and noise contributions, and is not related to the formation of gold|molecule|gold junctions. Introducing a “relative” distance of 1.25 nm as a threshold for the identification of
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Published 18 Oct 2011

Femtosecond time-resolved photodissociation dynamics of methyl halide molecules on ultrathin gold films

  • Mihai E. Vaida,
  • Robert Tchitnga and
  • Thorsten M. Bernhardt

Beilstein J. Nanotechnol. 2011, 2, 618–627, doi:10.3762/bjnano.2.65

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  • the investigations of the photodissociation dynamics are presented for the three molecular-adsorbate systems investigated. The characterization of the ultrathin gold films on Mo(100) that have been employed as a substrate in the present study is detailed in Supporting Information File 1. Adsorption of
  • observed for CH3I [10][18] and CH3Br [12] on MgO, CH3Br on LiF [19], and CH3Cl on Pd(100) [20], as well as for CH3Cl, CH3Br and CH3I on GaAs(110) [21][22], and the coverage dependence is attributed to the adsorbateadsorbate repulsion that results from the interaction between the static dipole moments of
  • adsorbed molecules. Due to this lateral repulsion between the adsorbate molecules, the activation energy for desorption decreases with increasing coverage and, hence, the desorption temperature decreases. The completion of the first monolayer of CD3I molecules appears for doses just below 4.75 L, in
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Published 20 Sep 2011

Nanostructured, mesoporous Au/TiO2 model catalysts – structure, stability and catalytic properties

  • Matthias Roos,
  • Dominique Böcking,
  • Kwabena Offeh Gyimah,
  • Gabriela Kucerova,
  • Joachim Bansmann,
  • Johannes Biskupek,
  • Ute Kaiser,
  • Nicola Hüsing and
  • R. Jürgen Behm

Beilstein J. Nanotechnol. 2011, 2, 593–606, doi:10.3762/bjnano.2.63

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  • the site-blocking adsorbate, however, is not clear from these experiments. It is likely that, similar to previous findings based on combined in situ IR and reaction measurements on dispersed Au/TiO2 catalysts [23], surface carbonates are mainly responsible for the deactivation [24][38][45][46
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Published 15 Sep 2011

Inorganic–organic hybrid materials through post-synthesis modification: Impact of the treatment with azides on the mesopore structure

  • Miriam Keppeler,
  • Jürgen Holzbock,
  • Johanna Akbarzadeh,
  • Herwig Peterlik and
  • Nicola Hüsing

Beilstein J. Nanotechnol. 2011, 2, 486–498, doi:10.3762/bjnano.2.52

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  • methyl-spacer samples and in the range of 270 cm3 g−1 for propyl-spacer samples (Table 1). The decreasing C-value, indicative of the adsorbent–adsorbate interactions, for gels prepared from a silica-precursor solution containing 3.0–6.0 mmol CMTMS follows the trend expected for gels with increasing
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Published 26 Aug 2011

Towards a scalable and accurate quantum approach for describing vibrations of molecule–metal interfaces

  • David M. Benoit,
  • Bruno Madebene,
  • Inga Ulusoy,
  • Luis Mancera,
  • Yohann Scribano and
  • Sergey Chulkov

Beilstein J. Nanotechnol. 2011, 2, 427–447, doi:10.3762/bjnano.2.48

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  • adsorbate frequencies from first principles. We give a detailed account of our local implementation of the vibrational self-consistent field approach and its correlation corrections. We show that our approach is both robust, accurate and can be easily deployed on computational grids in order to provide an
  • corresponding oscillation frequencies of this set of atoms are usually known as group frequencies and are characteristic of a particular structural motif. In heterogeneous catalysis, for example, the shift of the adsorbate vibrational frequencies allows us to follow the progress of surface reactions and
  • provides important information on the bond strength and location of the adsorbate. A typical example is carbon monoxide, which can be used as a surface probe, as the C=O stretch frequency is very sensitive to the adsorption site of the molecule. This property was identified very early on, and was used by
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Published 10 Aug 2011

Septipyridines as conformationally controlled substitutes for inaccessible bis(terpyridine)-derived oligopyridines in two-dimensional self-assembly

  • Daniel Caterbow,
  • Daniela Künzel,
  • Michael G. Mavros,
  • Axel Groß,
  • Katharina Landfester and
  • Ulrich Ziener

Beilstein J. Nanotechnol. 2011, 2, 405–415, doi:10.3762/bjnano.2.46

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  • for 2,2'-BTP (5) at the HOPG/TCB solution interface. To further support the experimental results, force field calculations of the square symmetric adsorbate layers of 2,4'-BTP (2) and 2,2'-BTP (5) were performed. The results of these calculations underline their structural similarities: For both
  • ovals. Adsorbate structures of 2,4'-BTP (2) (left) and 2,2'-BTP (5) (right) in the square symmetric structure, optimized with the Compass [32] force field. a) 15 × 15 nm2 STM image (Iset = 3.41 nA, Vset = −660 mV) of 2,2'-PhSpPy (14) at the HOPG/TCB interface [a = 3.0 ± 0.1 nm, b = 3.0 ± 0.1 nm, a,b
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Published 26 Jul 2011
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