Surface Structure and Stability

Manning, B.A. Goldberg, S. (1996) Modeling competitive adsorption of arsenate with phosphate and molybdate on oxide minerals. Soil Sci. Soc. Am. J. 60 121-131 Manning, B.A. Fendorf S.E. Goldberg, S. (1998) Surface structures and stability of ar-senic(lll) on goethite spectroscopic evidence for inner-sphere complexes. Environ. Sci. Techn. 34 2383-2388... 

Supported Cu-Pd catalysts have the potential to provide new alternatives to conventional commercial methanol synthesis catalysts (based on the Cu-ZnO-alumina system). Cu-Pd catalysts are also of industrial interest in hydrogenolysis and CO oxidation (Bulatov 1995). To interpret the catalyst behaviour and selectivity, including CO hydrogenation, a fundamental understanding of the structure, surface structure and stability of the phases in this system is required. The Cu-Pd phase diagram indicates that at temperatures greater than 600 °C, Cu... 

BA Manning, SE Fendorf and S Goldberg. Surface structures and stability of arsenic... 

BA Maiming, SE Eendorf, S. Goldberg. Surface structures and stability of arsenic (III) on goethite Spectroscopic evidence for inner-sphere complexes. Environ Sci Technol 32 2383-2388, 1998. 

Manning, B. A., S. E. Fendorf, and S. Goldberg. 1998. Surface structures and stability of Arsenic(III) on Goethite Spectroscopic evidence for iimer-sphere complexes. Environmental Science and Technology 32, no. 16 2383-2388. doi 10.1021/ es9802201. 

In this work, we first sketch the fundamental aspects of chemisorbed SAMs as a tool for building complex molecular systems. Using thiol SAMs as model systems, we first briefly review the self-assembly, surface structure, and stability under different experimental conditions. We also point out the characteristics of SAMs that make them suitable especially for building active micro- and nano-structured molecular systems on surfaces, and stress their limitations resulting from defects, contaminants, and disorders. Finally, we present examples of interfacial architectures drawn from supramolecular and covalent systems to illustrate the potential of SAMs as robust platforms for functional 3D structures on solid substrates. 

The many papers in this proceedings are partitioned into very abstruse theoretical analyses of structure and stability of quasicrystals on the one hand, and practical studies of surface structures, mechanical properties and potential applications. The subject shows signs of becoming as deeply divided between theorists and practical investigators, out of touch with each other, as magnetism became in the preceding century. 

Shi, H. and Stampfl, C. (2007) First-principles investigations of the structure and stability of oxygen adsorption and surface oxide formation at Au(lll). Physical Review B Condensed Matter, 76, 075327-1-075327-14. 

Fedak DG, Gjostein NA. 1966. Structure and stability of (100) surfaces of gold. Phys Rev Lett 16 171-172. 

As is known, if one blows air bubbles in pure water, no foam is formed. On the other hand, if a detergent or protein (amphiphile) is present in the system, adsorbed surfactant molecules at the interface produce foam or soap bubble. Foam can be characterized as a coarse dispersion of a gas in a liquid, where the gas is the major phase volume. The foam, or the lamina of liquid, will tend to contract due to its surface tension, and a low surface tension would thus be expected to be a necessary requirement for good foam-forming property. Furthermore, in order to be able to stabilize the lamina, it should be able to maintain slight differences of tension in its different regions. Therefore, it is also clear that a pure liquid, which has constant surface tension, cannot meet this requirement. The stability of such foams or bubbles has been related to monomolecular film structures and stability. For instance, foam stability has been shown to be related to surface elasticity or surface viscosity, qs, besides other interfacial forces. 

Spadini, L. Manceau, A. Schindler, P.W. Charlet, L. (1994) Structure and stability of Cd surface complexes on ferric oxides. 1. Results from EXAFS spectroscopy. J. Colloid Interface Sd. 168 78—86... 

The structure and stability of foamed emulsions, such as whipped cream, ice cream or whipped toppings, strongly depend on the interparticle interactions and on the orientation of drops/particles at the foam films. Further development of the surface force balance and... 

There is little question that one of the most active research areas in materials science is studying interfaces. In the past, emphasis in materials science has been placed on relating the bulk properties to the structure and composition of the solid. Today, efforts are in progress that relate surface reactivity and stability to the crystallographic orientation and composition, primarily at the S/G interface. Since a fundamental understanding of interfacial behavior and degradation mechanisms at an atomistic level is necessary if short-time test data are to be extrapolated to 30-year lifetimes, careful studies at the S/S, S/G, and S/L interfaces are required (4). 

There is substantial history regarding the application of conventional vibrational spectroscopy methods to study the intact surface of skin, the extracted stratum corneum and the ceramide-cholesterol-fatty acid mixtures that constitute the primary lipid components of the barrier. The complexity of the barrier and the multiple phases formed by the interactions of the barrier components have begun to reveal the role of each of these substances in barrier structure and stability. The use of bulk phase IR to monitor lipid phase behavior and protein secondary structures in the epidermis, as well as in stratum corneum models, is also well established 24-28 In addition, in vivo and ex vivo attenuated total reflectance (ATR) techniques have examined the outer layers of skin to probe hydration levels, drug delivery and percutaneous absorption at a macroscopic level.29-32 Both mid-IR and near-IR spectroscopy have been used to differentiate pathological skin samples.33,34 The above studies, and many others too numerous to mention, lend confidence to the fact that the extension to IR imaging will produce useful results. 

The experimental detection and quantitation of surface species on soil particles and other natural colloids is a difficult area of research because of sample heterogeneity, low surface concentrations and the need to investigate solid adsorbents in the presence of liquid water. Unambiguous information about the molecular structure and stability of adsorbed species can be obtained only with in situ surface spectroscopy (see also Chapter 3). Invasive spectroscopic methods that require sample desiccation or high-vacuum techniques (e.g. electron microscopy, X-ray... 

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