Search results for "layer"

Polymer-supported bilayer on a solid substrate

1992

Ab initio modeling of copper adhesion on regular BaTiO3(001) surfaces

2005

Ab initio calculations have been performed for copper adsorption on a regular, defect-free TiO"2- and BaO-terminated (001) surfaces of a cubic BaTiO"3, using a posteriori HF-CC method as implemented into the CRYSTAL-03 computer code. To clarify the nature of the interfacial bonding, we use slab models of the Cu/BaTiO"3(001) interfaces with different one-side substrate coverages, varied from 1/8 monolayer (ML) up to 1/2 ML, over both TiO"2- and BaO-terminated surfaces. TiO"2 termination has been found to be energetically more favorable for the adsorption of copper atoms. In agreement with previous experimental and theoretical data, our calculations indicate essential contribution of atomic p…

ChemInform Abstract: Catenanes and Threaded Systems: From Solution to Surfaces

2009

Functional catenanes and threaded systems able to perform controllable mechanical motions are ideally suited for the design of molecular devices displaying mechanical, electronic, information or sensing functions. These systems have been extensively studied in solution phase and numerous examples of stimuli-driven molecular shuttles have been reported. However, for fully developing their potential applications, they must be interfaced with the macroscopic world. To achieve this objective, in the last few years catenanes and rotaxanes have been organized over surfaces in the form of chemisorbed monolayers or physisorbed monolayers, multilayers and thin films. This tutorial review summarizes …

Electrocrystallization of Monolayer-Protected Gold Clusters : Opening the Door to Quality, Quantity, and New Structures

2017

Thiolate-protected metal clusters are materials of ever-growing importance in fundamental and applied research. Knowledge of their single-crystal X-ray structures has been instrumental to enable advanced molecular understanding of their intriguing properties. So far, however, a general, reliable, chemically clean approach to prepare single crystals suitable for accurate crystallographic analysis was missing. Here we show that single crystals of thiolate-protected clusters can be grown in large quantity and very high quality by electrocrystallization. This method relies on the fact that charged clusters display a higher solubility in polar solvents than their neutral counterparts. Nucleation…

Sterols and Steroids

1994

Sterols and steroids, like the terpenes and carotinoids, are isoprene derivatives. The sterols are components of the membranes of all eukaryotic cells and they bind and condense the phospholipid bilayer. The outer cell membrane is particularly rich in sterols, with a molar ratio of sterols to phospholipids of 0.8–0.1, compared with the usual value of 0.1–0.3 for intracellular membranes. The parent substance of all sterols is cholesterol (Fig. 16.1). The sterols are classified with the steroid hormones and bile salts as steroids because they also have the gonan (formerly steran) four-ring system and have their biosynthetic origin in cholesterol. Steroids with hormonal functions are known fro…

Study of interface diffusion of Ti and TiN PVD layers by Bremsstrahlung-induced AES

1992

The influence of heat treatment in ultrahigh vacuum (UHV) on Ti and TiN layers coated by physical vapour deposition (PVD) has been studied by AES, XPS and bremsstrahlung-induced AES. It could be concluded that up to 500 o C (1 h) the Ti layer does not change significantly. At the TiN/steel substrate interface, however, a counter-diffusion of nitrogen and adventitious oxygen takes place, resulting in partial nitridation of the steel substrate and oxidation of the coating

Hartree–Fock study of adhesion and charge redistribution on the Ag/MgO(0 0 1) interface

2001

Abstract Ab initio study of the Ag/MgO(0 0 1) interfaces based on a quantitative analysis of the bonding in the interfacial region is provided in the framework of Hartree–Fock approach. We are describing the way interfacial electronic and other properties evolve as a function of metal coverage. General conclusion that could be drawn from our calculations is that chemical bond formation is not important for the Ag/MgO(0 0 1) perfect interface. Physisorption of Ag atoms over surface O 2− ions associated with atomic polarization and charge redistribution in the metal planes are the dominant effects. The adhesion energy is enhanced by the interaction of the substrate Mg 2+ ions with the surplus…

First principles slab calculations of the regular Cu/MgO(001) interface

2004

Ab initio slab calculations are performed for the copper adhesion over magnesium ions on the perfect MgO(0 0 1) surface with 1/4 monolayer (ML), two types of 1/2 ML and 1 ML substrate coverages. Results of our calculations are compared with various experimental and theoretical data. Both small atomic polarization and charge redistribution give the dominant contributions to the physisorption bonding on a regular Cu/MgO(0 0 1) interface.

CEMS/XPS study of iron stearate Langmuir-Blodgett layers

1991

Langmuir-Blodgett mono- and multilayers of ferric stearate have been formed on oxidized silicon wafers. Thermodesorption of these layers was investigated by conversion electron Mossbauer and photoelectron spectroscopy and some complementary methods. Heating of samples in air up to 523 K leads to a desorption of the fatty acid chains, while the ferric ions are left on the substrate surface. These ions do not cluster laterally like it was found for Cd ions. They form a rather homogeneous, closed oxidic layer. This well defined layer may be used afterwards for further studies of surface reactions as well as interface and intra-layer interactions. The surface iron ions were found to exhibit a r…

Hybrid Materials Based on Magnetic Layered Double Hydroxides: A Molecular Perspective

2015

Design of functional hybrids lies at the very core of synthetic chemistry as it has enabled the development of an unlimited number of solids displaying unprecedented or even improved properties built upon the association at the molecular level of quite disparate components by chemical design. Multifunctional hybrids are a particularly appealing case among hybrid organic/inorganic materials. Here, chemical knowledge is used to deploy molecular components bearing different functionalities within a single solid so that these properties can coexist or event interact leading to unprecedented phenomena. From a molecular perspective, this can be done either by controlled assembly of organic/inorga…