Surface techniques, applications

P. R. Griffiths and J. A. de Haseth. Fourier Transfrsrm Infrared Spectrometry John Wiley Sons, New York, 1986. Chapters 1—8 review FTIR equipment in considerable detail. Chapters 9-19 describe applications, including surface techniques (Chapter 17). 

Considerable progress has been made recently In the development of In situ spectroscopic techniques applicable to the study of transition metal macrocycles adsorbed at submonolayer coverages onto electrode surfaces. These have been aimed at gaining Insight into the nature of the Interactions of these compounds with the surface and with 02 Most of the attention In the authors laboratory has been focused on Fe- and Co-TsPc, although some preliminary results have already been obtained for some Iron and cobalt porphyrins. The main conclusions obtained from these Investigations will be outlined In the following sections. 

Werpetinski, K. S., Cook, M., 1997, A New Grid-Free Density Functional Technique Application to hie Torsional Energy Surfaces of Ethane, Hydrazine, and Hydrogen Peroxide , J. Chem. Phys., 106, 7124. 

Mark A. Barteau is Robert L. Pigford Professor and Chair of the Department of Chemical Engineering at the University of Delaware. He received his B.S. degree from Washington University in 1976 and his M.S. (1977) and Ph.D. (1981) from Stanford University. His research area is chemical engineering with specialized interests in application of surface techniques to reactions on nonmetals, hydrocarbon and oxygenate chemistry on metals and metal oxides, scanning probe microscopies, and catalysis by metal oxides. 

SIMS is by far the most sensitive surface technique, but also the most difficult one to quantify. SIMS is very popular in materials research for making concentration depth profiles and chemical maps of the surface. The principle of SIMS is conceptually simple A primary ion beam (Ar+, 0.5-5 keV) is used to sputter atoms, ions and molecular fragments from the surface which are consequently analyzed with a mass spectrometer. It is as if one scratches some material from the surface and puts it in a mass spectrometer to see what elements are present. However, the theory behind SIMS is far from simple. In particular the formation of ions upon sputtering in or near the surface is hardly understood. The interested reader will find a wealth of information on SIMS in the books by Benninghoven et al. [2J and Vickerman el al. [4], while many applications have been described by Briggs et al. [5]. 

Applications of Surface Techniques to Chemical Bonding Studies of Minerals... 

Perry, D. L. "Application of Surface Techniques to Chemical Bonding Studies of Geologic Materials," Davis, J. A. and Hayes, K. F., eds., ACS Symposium Series, 1986. 

The following table summarizes techniques useful for the study of oxide surfaces (20), Applications of a number of these are described in the papers by Volta, et al, Busca, Deo and Wachs, Okuhara, et al, A transient technique is reported by Rigas, et al. 

The heart of the polarization-modulated nephelometer is a photoelastic modulator, developed by Kemp (1969) and by Jasperson and Schnatterly (1969). The latter used their instrument for ellipsometry of light reflected by solid surfaces (the application described here could be considered as ellipsometry of scattered light). Kemp first used the modulation technique in laboratory studies but soon found a fertile field of application in astrophysics the modulator, coupled with a telescope, allowed circular polarization from astronomical objects to be detected at much lower levels than previously possible. 

As with the electron microprobe, the chemical composition is determined through comparison with standards. Corrections for interactions with different elements are also necessary. However, the standardization and correction procedures for the AES are much less mature than those for the electron probe. In cosmochemistry, the auger nanoprobe is used primarily to determine the chemical compositions of presolar grains. It is ideal for this application because it is a surface technique and has the same spatial resolution as the NanoSIMS (see below), which is used to identify presolar grains in situ in meteorite samples and IDPs. 

The techniques used in studying interfaces can be classified in two categories in situ techniques and ex situ techniques. In situ methods are those where a surface is probed by one or several techniques while immersed in solution and under potential control. In contrast, in ex situ methods, an electrochemical experiment is first carried out. Then the electrode is removed from solution and examined by one or several spectroscopic techniques, which generally require ultrahigh vacuum (UHV) conditions. Figures 6.10 and 6.11 show some of the most common ex situ and in situ techniques applicable to the study of the metal/solution interface. 

A large variety of problems related to the nature of the adsorption processes have been studied by infrared spectroscopy. The most extensive and productive application of this method has been in studies of chemisorption on supported-metal samples. Spectra of physically adsorbed molecules have provided important information on the interaction of these molecules with the surface of the adsorbent. Experimental developments have reached a state where it is evident that the infrared techniques are adaptable to practically all types of samples which are of interest to catalytic chemists. Not only are the infrared techniques applicable to studies of chemisorption and physical adsorption systems but they add depth and preciseness to the definitions of these terms. 

In the case of solid electrodes, knowledge of the real surface area is a prerequisite for the proper evaluation of the activity with respect to other samples from the same laboratory, or for the comparison of results from different laboratories. It is very difficult to determine the real surface area because there are no unique techniques applicable to all materials. When the surface area determination is lacking, an evaluation in terms of synergetic effects can only be ambiguous. 

However, this article is not intended to provide an exhaustive review of the voluminous literature on the application of surface analytical techniques to semiconductor problems. Numerous reviews have been published which have treated various aspects of these applications (1-jj). This article is intended to give an overview, drawing from more recent publications, of the ways in which surface analysis continues to play a vital role in the development and application of the numerous material technologies involved in semiconductor processes. In addition, the need for further development of surface techniques and a summary of the materials problem that do not lend themselves to the available analytical techniques are described. 

The specific natures of surface techniques and, in some cases, their applications to corrosion have been discussed by a number of authors. General use of surface tools in Corrosion has been discussed by Larson (8), Joshi (j), 10) and in the PHI Interface Volume 3 2 (1980). There has been considerable application of surface methods to electrochemical corrosion (11-15) including use of various types of vacuum compatible corrosion cells (16,... 

Understanding particle adhesion to a surface has applications in tissue engineering and particle processing. Experimental techniques for charactering particle adhesion to surfaces include laser trapping, AFM and microscopy with force measurement. 

Using XRF and EPMA in conjunction with SEM and EDX the antiwear films were found to consist of P, S, O, and Zn (Brown et al., 1992 Rounds, 1993). The application of XPS and AES surface techniques promoted deeper understanding of the antiwear mechanism elemental composition of the chemical species, valence of the elements, and depth distribution. Chemical speciation, e.g., phosphate and S (sulfide or sulfate) can be obtained from binding energies. 

In research on the mechanisms gouverning the modification reactions, the thin silica layers allow the application of various surface analytical techniques, which are of no use for analysis inside porous systems. Reaction mechanisms are simplified by the elimination of porosity and may be studied by direct surface techniques such as ellipsometry, as well as microscopic techniques such as Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM).59... 

Surface modification via chemical reactions is currently a very active field due to potential applications in the development of new materials. In addition to the ene and diene systems, other surface reactions including ionic, radical and photochemical reactions with a variety of functional groups are expected to extend the scope of potentially useful surface techniques. 

Secondary ion mass spectrometry (SIMS) is a highly sensitive surface technique for characterizing materials. The procedure is based on the mass analysis of ions created when an impinging beam strikes the surface of a solid (or liquid, in a few special applications). The impinging ion beam, usually referred to as the primary ion beam, is generally accelerated to energies between 0.2 and 40 keV. Figure 4.1 shows the essential elements of SIMS. 

The methods widely used in characterizing the surface grafting onto films are UV, attenuated total reflection (ATR) IR, X-ray-photoelectric spectroscopy (ESCA), contact angle measurement and other techniques applicable to the characterization of the surface treatments of polymeric substances. 

Raman spectroscopy failed to live up to its original expectation when the technique was discovered. This was due to instrumental problems, high cost of the instrument, and the fluorescence problem. However, with improvement in instrumentation, the use of a near infrared laser with FT-Raman, the introduction of fiber optics, the number of applications (some of which were discussed in Chapter 3) has escalated. The applications are expanded in this chapter, which deals with materials applications involving structural chemistry, solid state, and surfaces. Additional applications are presented in Chapter 5 (analytical applications), Chapter 6 (biochemical and medical applications) and Chapter 7 (industrial applications). 

The scope of the chapter will include an introduction to the technique of neutron reflectometry, and how it is applied to the study of surfactant adsorption at the planar solid-solution interface, to obtain adsorbed amounts and details of the structure of the adsorbed layer. The advantages and limitations of the technique will be put in the context of other complementary surface techniques. Recent results on the adsorption of a range of anionic, cationic and nonionic surfactants, and surfactant mixtures onto hydrophilic, hydrophobic surfaces, and surfaces with specifically tailored functionality will be described. Where applicable, direct comparison with the results from complementary techniques will be made and discussed. 

Preformed sticks or tubes of solid epoxy may also be applied much as a solder is.6 To apply, the area to be bonded is heated until sufficiently hot to cause the stick solder to flow when drawn across the surface. After application, the adhesive is cured by conventional thermal techniques. If two substrates are to be bonded, both must be preheated prior to... 

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