Surface physics

We attempt to delineate between surface physical chemistry and surface chemical physics and solid-state physics of surfaces. We exclude these last two subjects, which are largely wave mechanical in nature and can be highly mathematical they properly form a discipline of their own. 

We also attempt to distinguish between surface physical chemistry and colloid and polymer physical chemistry. This distinction is not always possible, and clearly many of the features of physical chemistry of surfaces, such as the electrostatic interactions and adsorption of macromolecules, have a significant... 

Clearly, the physical chemistry of surfaces covers a wide range of topics. Most of these subjects are sampled in this book, with emphasis on fundamentals and important theoretical models. With each topic there is annotation of current literature with citations often chosen because they contain bibliographies that will provide detailed source material. We aim to whet the reader s appetite for surface physical chemistry and to provide the tools for basic understanding of these challenging and interesting problems. 

Himpsei F J 1991 Unoccupied eiectronic states at surfaces Surface Physics and Related Topics. Festschrift for Xide Xie ed F-J Yang, G-J Ni, X Wang, K-M Zhang and D Lu (Singapore Worid Scientific) p 179... 

Lagaiiy M G 1993 Atom motion on surfaces Physics Today 46 24... 

A uniform coating of calcium carbonate deposited on the metal surfaces physically segregates the metal from the corrosive environment. To develop the positive LSI required to deposit calcium carbonate, it is usually necessary to adjust the pH or calcium content of the water. Soda ash, caustic soda, or lime (calcium hydroxide) may be used for this adjustment. Lime is usually the most economical alkaH because it raises the calcium content as weU as the alkalinity. 

Flotation is a physical process involving relative interaction of three phases solid, water, and air. An understanding of the wettability of the solid surface, physical surface, and chemical phenomena by which the flotation reagents act and the mechanical factors that determine particle-bubble attachment and removal of particle-laden bubbles, is helpful in designing and operating flotation systems successfully. 

M. Pmtton. Surface Physics, 2nd edn. Oxford University Piess (1983). 

Volume 39 Characterization of Porous Solids. Proceedings of the lUPAC Symposium (COPS I), Bad Soden a. Ts., April 26-29,1987 edited by K.K. Unger, J. Rouquerol, K.S.W. Sing and H. Krai Volume 40 Physics of Solid Surfaces 1987. Proceedings of the Fourth Symposium on Surface Physics, Bechyne Castle, September 7-11,1987 edited by J. Koukal... 

Since then, STM has been established as an insttument fot foteftont research in surface physics. Atomic resolution work in ultrahigh vacuum includes studies of metals, semimetals and semiconductors. In particular, ultrahigh-vacuum STM has been used to elucidate the reconstructions that Si, as well as other semiconducting and metallic surfaces undergo when a submonolayer to a few monolayers of metals are adsorbed on the otherwise pristine surface. ... 

Scanning probe microscopy is a forefront technology that is well established for research in surface physics. STM and SFM are now emerging ftom university laboratories and gaining acceptance in several industrial markets. For topographic analysis and profilometry, the resolution and three-dimensional nature of the data is... 

X-ray absorption spectroscopy is an important part of the armory of techniques for examining pure and applied problems in surface physics and chemistry. The basic physical principles are well understood, and the experimental methods and data analysis have advanced to sophisticated levels, allowing difficult problems to be solved. For some scientists the inconvenience of having to visit synchrotron radia-... 

K. Christmann. Introduction to Surface Physical Chemistry. Darmstadt Stein-kopffVerlag, 1991. 

The performance of VASP for alloys and compounds has been illustrated at three examples The calculation of the properties of cobalt dislicide demonstrates that even for a transition-metal compound perfect agreement with all-electron calculations may be achieved at much lower computational effort, and that elastic and dynamic properties may be predicted accurately even for metallic systems with rather long-range interactions. Applications to surface-problems have been described at the example of the. 3C-SiC(100) surface. Surface physics and catalysis will be a. particularly important field for the application of VASP, recent work extends to processes as complex as the adsorption of thiopene molecules on the surface of transition-metal sulfides[55]. Finally, the efficiciency of VASP for studying complex melts has been illustrate for crystalline and molten Zintl-phases of alkali-group V alloys. 

The last twenty years have seen a rapid development of surface physics. In particular, the properties of clean perfect surfaces (with two-dimensional periodicity) are henceforth well known and understood. In recent years, the focus has been put onto surfaces with defects (adatoms, steps, vacancies, impurities...) which can now be investigated experimentally due either to the progress of old techniques (field ion microscopy or He diffraction, for instance) or to the rapid development of new methods (STM, AFM, SEXAFS...). 

M. C. Desjonqueres and D. Spanjaard, Concepts in Surface Physics, Second Edition, Springer Verlag, Berlin (1996) and references therein R. Haydock, V. Heine and M. J. Kelly, Electronic Structure Based on the Local Atomic Environment for Tight-Binding Bands,. Phys. C 5 2845 (1972)... 

In addition to the surface physics and chemistry phenomena involved, a further effect may follow the interaction at the hydrogen-metal surface, that is the absorption of hydrogen by the bulk phase of the metal. This absorption leads to the formation of a solid solution within a certain, usually low, range of hydrogen concentrations. However, with several transition metals, exceeding a certain limit of hydrogen concentration results in the formation of a specific crystallographically distinct phase of the... 

Leamy HJ, Gilmer GH, Jackson KA (1975) in Blakely JM (ed) Surface physics of materials. Academic Press, London, p 121... 

Although liquid Hg would never be used as a reference (model) surface in surface physics because its liquid state and high vapor pressure do not allow appropriate UHV conditions, this metal turns out to be a reference surface in electrochemistry for precisely the same reasons reproducibility of the surface state, easy cleaning of its surface, and the possibility of measuring the surface tension (surface thermodynamic conditions). In particular, the establishment of a UHV scale for potentials is at present based on data obtained for Hg. 

E0so is measured in electrochemistry and is usually known with an accuracy to 0.01 V or better.8 On the other hand 0 is measured with surface physics techniques that have an accuracy of 0.05 eV, rarely better and often worse (because of imperfect surfaces)/9 Thus, Eq. (28) does not ensure an appropriate accuracy for AX, so that the uncertainty may outweigh the value itself. The best way to proceed is to plot E0=q vs. 0 for a number of metals and to derive information about AX from eventually recognizable graphical correlations using statistical analysis. 

J. Holzl, and F.K. Schulte, Work Function of Metals, in Solid Surface Physics, Springer-Verlag, Berlin (1979), pp. 1-150. 

To address these challenges, chemical engineers will need state-of-the-art analytical instruments, particularly those that can provide information about microstmctures for sizes down to atomic dimensions, surface properties in the presence of bulk fluids, and dynamic processes with time constants of less than a nanosecond. It will also be essential that chemical engineers become familiar with modem theoretical concepts of surface physics and chemistry, colloid physical chemistry, and rheology, particrrlarly as it apphes to free surface flow and flow near solid bormdaries. The application of theoretical concepts to rmderstanding the factors controlling surface properties and the evaluation of complex process models will require access to supercomputers. 

As noted before, thin film lubrication (TFL) is a transition lubrication state between the elastohydrodynamic lubrication (EHL) and the boundary lubrication (BL). It is widely accepted that in addition to piezo-viscous effect and solid elastic deformation, EHL is featured with viscous fluid films and it is based upon a continuum mechanism. Boundary lubrication, however, featured with adsorption films, is either due to physisorption or chemisorption, and it is based on surface physical/chemical properties [14]. It will be of great importance to bridge the gap between EHL and BL regarding the work mechanism and study methods, by considering TFL as a specihc lubrication state. In TFL modeling, the microstructure of the fluids and the surface effects are two major factors to be taken into consideration. 

Surface Physics, Bechyne Castle, September 7-11, 1987 edited by J.Koukal... 

R. Kotz reviews the application of the most powerful surface physics technique, photoelectron spectroscopy, for the elucidation of the composition of electrodes. He exemplifies the potential of this technique for materials which play a key role in electrochemical oxidation processes or are used in some other electrochemical process. 

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