Interface investigation methods

ATR is a surface and interface investigation method. The penetration depth is of the order of a few tenths of the wavelength of investigation, in the IR between 0.5 and 10 pm (cf Eq. (10) in Chapter 5). A variety of ATR accessories is available including various kinds of liquid cells or even horizontal units for cell-less investiga-... 

From the experimental results and theoretical approaches we learn that even the simplest interface investigated in electrochemistry is still a very complicated system. To describe the structure of this interface we have to tackle several difficulties. It is a many-component system. Between the components there are different kinds of interactions. Some of them have a long range while others are short ranged but very strong. In addition, if the solution side can be treated by using classical statistical mechanics the description of the metal side requires the use of quantum methods. The main feature of the experimental quantities, e.g., differential capacitance, is their nonlinear dependence on the polarization of the electrode. There are such sophisticated phenomena as ionic solvation and electrostriction invoked in the attempts of interpretation of this nonlinear behavior [2]. 

N. Kallay, V. Hlady, J. Jednacak-Biscan, and S. Miljonic, in Investigations of Surfaces and Interfaces Physical Methods of Chemistry Series, 2nd ed., John Wiley Sons, Inc., New York, 1993, pp. 73-140. 

FIGURE 3.2. Schematic diagram of the experimental set-up. (a) An enlarged sketch of the sample space, and (b) a block diagram of the TR-QELS method for liquid/liquid interface investigation. 

In order to investigate molecules adsorbed at the solid-liquid interface roughened electrode surfaces or metal colloids in solution (sols) are prepared. For investigations of the solid-gas or solid-vapour interface several methods are available to produce metal island films on SERS-active substrates. 

The influence of the distribution of electrolytes between water and oils on the electrical potential change at the interface has been investigated. Methods for comparing these potentials were developed and applied to a number of simple systems. 

Little is known about the detailed steps and their controls for reactions at the interface of reactant/product contact, for which investigative methods are difficult or unavailable. 

Very recently, this investigation method has been extended to two dimensions. Improvements have been made concerning the measurement technique of the surface osmotic pressure of polymers spread on a liquid-air interface. Vilanove and Rondelez thus measured, for the first time in 1980, the characteristic size exponent v of chains in a two-dimensional space. 

In the previous chapter, the equilibrium between the solid and the liquid phase was described. The interface between the two bulk phases is the mediator and any processes between the two neighboring phases wiU be influenced by the properties of this interface. In this chapter the properties of this interface and methods of investigation will be described. 

Surface photovoltage (SPV) measurements have been used to investigate electronic structures at the semiconductor surfaces for semiconductor-vacuum and semiconductor-gas interfaces. This method is applied to semiconductor-liquid interfaces in case of insulating liquids [39]. 

Fig. 2 Thermodynamics of the octadecanol (CijOH) monolayer films at the air/water (GS), and metal/solution (MS) interfaces investigated by the HT electrochemical methods. Three-dimensional representation of the film pressure at the MS interface as a function of the film pressure at the GS interface (at the time of an HT experiment in which a freshly flamed Au (111) electrode is placed at the GS interface), and the electrode potential. The straight line, drawn at = Epzc, represents conditions under which the surface pressure of the CigOH film is the same at both interfaces (from Ref. 28).

The contact of biomaterial surfaces with the biological system blood provokes, with different intensity, activation of the intrinsic coagulation pathway at the blood/biomaterial interface. Clinically important and reproducible investigation methods are carried out to evaluate blood compatibility. The following coagulation parameters, obtained after the contact of the foreign surface with native, non-anticoagulant human whole blood in a modified Bowry blood chamber [93] and compared to the initial citrate plasma values, are evaluated ... 

In order to find out as whether the lap-shear joint method may be used to measure y surface jn pigurc 7 are plotted the values of the lap-shear strength a for four symmetric polymer-polymer interfaces as a function of healing temperature at a chosen = 1 hr. As follows from Figure 7, the values of o for all the interfaces investigated decrease monotonically with a reduction in T, approaching a very small level of a (some hundredths of MPa) at r ° = 44°C (PS and PMMA), 64 = C (PET), and 90 = C (PPO), and, finally, dropping to o —>0. It means that diffusion did not occur at In terms... 

A related field of research where NMR investigations have yielded a large variety of information are soft colloidal volume systems, so-called association colloids, composed of amphiphilics (surfactants, lipids) or copolymers, e.g. block-copolymers. Structures such as micellar solutions, microemulsions, or liquid crystalline phases possess internal interfaces where the arrangement of molecules can be governed by similar principles as at a solid/liquid interface. NMR methods have very successfully been employed in this area, as has been reviewed [8, 9], and some ideas and approaches can be transferred to liquid interfacial layers in colloidal particle dispersions. 

The results presented earlier have clearly indicated that a molecular dynamic simulation enables one to observe all of the basic physical-chemical phenomena in the processes of wetting and spreading and enables one to conduct a rigorous analysis of the molecular mechanisms of various interactions taking place at the interfaces. The method of molecular dynamics offers a unique opportunity to study the mechanisms of the interfacial phenomena at a microscopic level. The equilibrium state of interfacial phenomena can be investigated using statistical methods, such as a Monte Carlo simulation [29]. 

Morishita T., Hibara A., Sawada T., Tsuyumoto 1. Ultrafast charge transfer at Ti02/SCN (aq) interfaces investigated by femtosecond transient reflecting grating method. J. Phys. Chem. B 1999 103 5984-5987... 

Ellipsometry is an optical monolayer-sensitive interface analysis method for the investigation of various aspects of surface and interfaces, including surface stoichiometry, surface roughness, adsorption, desorption, and surface strain, etc. In combination with the availability of microcomputers, SE has been developed and widely used for studies of thin films in the ambient, where parameters such as film thickness, composition, and interface roughness are determined. SE is now a popular tool for in situ growth control and diagnostics of interfaces. 

A number of methods that provide information about the structure of a solid surface, its composition, and the oxidation states present have come into use. The recent explosion of activity in scanning probe microscopy has resulted in investigation of a wide variety of surface structures under a range of conditions. In addition, spectroscopic interrogation of the solid-high-vacuum interface elucidates structure and other atomic processes. 

B. W. Rossiter and R. C. Baetzold, eds.. Physical Methods of Chemistry, Vol. IXA, Investigations of Surfaces and Interfaces, Wiley, New York, 1993. 

Krolil, H.U., Stifter, T., Waschipky, H., Weishaupt, K., Hild, S. and Marti, O., Pulsed force mode a new method for the investigation of surface properties. Surf. Interface Anal, 27(5-6), 336-340 (1999). 

Interfaces between water and a variety of different inorganic solids have been investigated by simulation methods. In the following, a brief review of key references and findings is given. The list of references is not necessarily complete and the interested reader should consult the work cited and references therein in order to find out more about the subject. 

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