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The co-adsorption of submono-, mono- and multi-layers of Cu with sulfate anions on a Au(111) electrode surface was investigated in electrochemical environment (0.1 mM CuSO 4 + 0.1 M H 2 SO 4 ) by cyclic voltammetry (CV) and in-situ scanning tunneling microscopy (STM). Correlated with the STM investigations the CV measurements indicate co-adsorption/-desorption processes of Cu of submono-, mono- and multi-layer coverages with sulfuric acid species on Au(111). The formation of a quasi-hexagonal Moiré superstructure on terraces of copper multilayers was observed in situ by STM. In detail the observed Moiré-structure is similar but not identical to the one observed on the (111) surface of bulk copper. High resolution STM images show the formation of a 3 × 7 -like sulfate structure on all multilayer copper terraces. [ABSTRACT FROM AUTHOR]

Abstract: Concentration of solute and polarity of solvent are vital parameters in controlling self-assembled structure formation of molecules at solid–liquid interfaces. Here we compare polymorphs of trimesic acid (TMA) obtained from different solvents as well as different concentrations at liquid–graphite interfaces. Solvents with different polarity like phenyloctane, fatty acids and fatty alcohols are used to dissolve TMA. From solvents with non-polar groups (as phenyloctane) TMA forms only a high-density structure; however, from solvents with moderate polar functional groups (as octanoic acid) there appear concentration-induced polymorphs. From solvents containing strong polar groups (as undecanol) there appears a mixed structure consisting of TMA and solvent molecules coadsorbed due to strong inter-molecular interaction. The concentration of all solutions is controlled by the time of sonication of the solute–solvent mixture. [Copyright &y& Elsevier]

Abstract: The specific adsorption of chloride on Cu(111) from acidic aqueous electrolyte (pH 3) was investigated by in-situ surface X-ray diffraction, revealing an incommensurate hexagonal rotated adlayer. The structure and its potential dependence suggest a strong adsorbate–adsorbate interaction as compared to other halide adlayers on (111)-oriented metal electrode surfaces. The orientational epitaxy can be rationalized by the model suggested by Grey and Bohr (Europhys. Lett. 18, 171, 1992), which is based on symmetry considerations. [Copyright &y& Elsevier]

Abstract: The structure of propanethiol self-assembled monolayers (SAMs) on Au(100) in 0.1M H2SO4 has been investigated as a function of electrode potential by in situ scanning tunnelling microscopy (STM). These studies reveal a potential-induced, reversible transition between an in essence quadratic and a distorted hexagonal structure. We suggest that a thiolate-driven surface reconstruction, similar to Au(100)-(hex), is responsible for the hexagonal SAM structure, whereas the quadratic one refers to the unreconstructed substrate. [Copyright &y& Elsevier]

Abstract: The self-assembly of meso-tetra (N-methyl-4-pyridyl) porphyrine tetratosylat (H2TMPyP) on an iodide modified Cu(111) surface has been studied by means of in situ electrochemical-scanning tunneling microscopy (EC-STM). The I/Cu(111) surface was found to be a good substrate for the self-assembly of highly ordered layers of porphyrin cations. Furthermore, a reversible structural phase transition within the highly ordered porphyrin layer was observed during variation of the electrode potential, as a consequence of changing electronic properties of the substrate. [Copyright &y& Elsevier]

Abstract: In situ electrochemical scanning tunneling microscopy (STM) has been used to examine the structures of benzenethiol adlayers on Au(100) and Pt(100) electrodes in 0.1M HClO4, revealing the formation of well-ordered adlattices of Au(100)-(√2×√5) between 0.2 and 0.9V and Pt(100)-(√2×√2)R45° between 0 and 0.5V (versus reversible hydrogen electrode), respectively. The coverage of Au(100)-(√2×√5) is 0.33, which is identical to those observed for upright alkanethiol admolecules on Au(111). In comparison, the coverage of Pt(100)-(√2×√2)R45° – benzenethiol is 0.5, much higher than those of thiol molecules on gold surfaces. This result suggests that benzenethiol admolecules on Pt(100) could stand even more upright than those on Au(100). All benzenethiol admolecules were imaged by the STM as protrusions with equal corrugation heights, suggesting identical molecular registries on Au(100) and Pt(100) electrodes, respectively. Modulation of the potential of a benzenethiol-coated Au(100) electrode resulted in irreversible desorption of admolecules at E ⩽0.1V (vs. reversible hydrogen electrode) and oxidation of admolecules at E ⩾0.9V. In contrast, benzenethiol admolecule was not desorbed from Pt(100) at potentials as negative as the onset of hydrogen evolution. Raising the potential rendered deposition of more benzenethiol molecules before oxidation of admolecules commenced at E >0.9V. [Copyright &y& Elsevier]

Abstract: Hexagonal mesoporous silicas chemically modified with ethylenediamine moieties were synthesized through the co-condensation of tetraethylorthosilicate (TEOS) with two different silylating agents: (i) N-[3-(trimethoxysilyl)propyl]-ethylenediamine and (ii) the new agent prepared from the incorporation of the ethylenediamine molecule into the epoxide group of the precursor 3-glycidoxypropyltrimethoxysilane. From these silylating agents under neutral n-octylamine template methodology, the respective MNN and MGNN inorganic–organic hybrids were synthesized. Elemental analysis showed that the number of pendant groups in these hybrids were 1.69 and 1.62mmolg−1, with pore diameters and surface areas of 1.81 and 1.53nm and 663±14 and 614±16m2 g−1. Infrared spectroscopy, nuclear magnetic resonance for 13C and 29Si nuclei and X-ray diffraction patterns are in agreement with the success of the proposed synthetic methods, as confirmed for the formation of the mesoporous hybrids. Both mesoporous materials have been used for divalent copper adsorption from aqueous solution at 298±1K. The series of adsorption isotherms were adjusted to a modified Langmuir equation. The maximum number of moles adsorbed gave 1.4±0.1 and 1.4±0.2mmolg−1 for MNN and MGNN, respectively. The same interactions were calorimetrically followed and gave exothermic enthalpy, negative Gibbs free energy and positive entropy values. These favorable thermodynamic data indicate cation/nitrogen basic center interactions on the new mesoporous materials at the liquid/solid interface for both systems. [Copyright &y& Elsevier]

Abstract: Interaction of condensed water molecules with hydroxyl and hydrogen groups on Si(001) was investigated using high-resolution electron energy-loss spectroscopy (HREELS) in an ultrahigh vacuum system and also slab model calculations based on the density functional theory (DFT). Equal amounts of the hydroxyl and hydrogen groups were formed via dissociative adsorption of water molecules on a reconstructed Si(001)-(2×1) surface. The interaction between the hydroxyl group and condensed water molecules was clearly observed in vibrational peak shifts of the hydroxyl group, while the hydrogen group showed little interaction, reflecting its hydrophilic or hydrophobic property, respectively. [Copyright &y& Elsevier]

Abstract: Sum frequency generation (SFG) vibrational spectroscopy has been applied to examine the molecular structures of proteins adsorbed at various interfaces, especially polymer/protein solution interfaces in situ. A thin film model was adopted to interpret interfacial protein SFG spectra. A polarization mapping method was developed that can help to analyze complicated protein SFG spectra more reliably, from which more structural information of various interfacial proteins can be deduced. SFG signals in different frequency ranges, including C–H, N–H, O–H stretching and amide I ranges, can be collected from proteins at interfaces. Different proteins, including bovine serum albumin, ubiquitin, fibrinogen, factor XII, and some selectively or randomly deuterated proteins, have been examined in SFG studies. Our research shows that proteins can have different conformations at various interfaces, and also that time-dependent structural changes of proteins after adsorption can be varied. SFG can be developed into a powerful and unique technique to elucidate interfacial protein structures at the molecular level in situ after continued success in the application of SFG to examine interfacial protein structures. [Copyright &y& Elsevier]