Electron spectroscopy, analytical method

Ultraviolet-visible (UV-VIS) spectroscopy Analytical method based on transitions between electronic energy states in molecules. Useful in studying conjugated systems such as polyenes. 

Materials characterization techniques, ie, atomic and molecular identification and analysis, ate discussed ia articles the tides of which, for the most part, are descriptive of the analytical method. For example, both iaftared (it) and near iaftared analysis (nira) are described ia Infrared and raman SPECTROSCOPY. Nucleai magaetic resoaance (nmr) and electron spia resonance (esr) are discussed ia Magnetic spin resonance. Ultraviolet (uv) and visible (vis), absorption and emission, as well as Raman spectroscopy, circular dichroism (cd), etc are discussed ia Spectroscopy (see also Chemiluminescence Electho-analytical techniques It unoassay Mass specthot thy Microscopy Microwave technology Plasma technology and X-ray technology). 

A detailed account is given in Reference 20. The techniques giving the most detailed 3-D stmctural information are x-ray and neutron diffraction, electron diffraction and microscopy (qv), and nuclear magnetic resonance spectroscopy (nmr) (see Analytical methods Magnetic spin resonance X-ray technology). 

Instrumental Methods for Bulk Samples. With bulk fiber samples, or samples of materials containing significant amounts of asbestos fibers, a number of other instmmental analytical methods can be used for the identification of asbestos fibers. In principle, any instmmental method that enables the elemental characterization of minerals can be used to identify a particular type of asbestos fiber. Among such methods, x-ray fluorescence (xrf) and x-ray photo-electron spectroscopy (xps) offer convenient identification methods, usually from the ratio of the various metal cations to the siUcon content. The x-ray diffraction technique (xrd) also offers a powerfiil means of identifying the various types of asbestos fibers, as well as the nature of other minerals associated with the fibers (9). 

Each type of mass spectrometer has its associated advantages and disadvantages. Quadrupole-based systems offer a fairly simple ion optics design that provides a certain degree of flexibility with respect to instrument configuration. For example, quadrupole mass filters are often found in hybrid systems, that is, coupled with another surface analytical method, such as electron spectroscopy for chemical analysis or scanning Auger spectroscopy. 

This kind of estimation of the relative concentration is the most widely used method for quantitative EELS analysis. It is advantageous because the dependence on the primary electron current, Iq, is cancelled out this is not easily determined in a transmission electron microscope under suitable analytical conditions. Eurthermore, in comparison with other methods, e. g. Auger electron spectroscopy and energy-disper-... 

The modern electronic industry has played a very important role in the development of instrumentation based on physical-analytical methods As a result, a rapid boom in the fields of infrared, nuclear magnetic resonance (NMR), Raman, and mass spectroscopy and vapor-phase (or gas-liquid) chromatography has been observed. Instruments for these methods have become indispensable tools in the analytical treatment of fluonnated mixtures, complexes, and compounds The detailed applications of the instrumentation are covered later in this chapter. 

Spoto, G. and E. Ciliberto (2000), X-ray photoelectron spectroscopy and Auger electron spectroscopy in art and archaeology, in Ciliberto, E. and G. Spoto (eds.), Modern Analytical Methods in Art and Archaeology, Chemical Analysis Series, Vol. 155, Wiley, New York, pp. 363 404. 

The structure of the catalysts was characterized by X-ray diffraction, IR-spectroscopy and transmission electron microscopy, their thermal stability was followed by thermal analytical method. The specific surface area and pore size distribution of the samples were determined by nitrogen adsorption isotherms. 

All analytical methods that use some part of the electromagnetic spectrum have evolved into many highly specialized ways of extracting information. The interaction of X-rays with matter represents an excellent example of this diversity. In addition to straightforward X-ray absorption, diffraction, and fluorescence, there is a whole host of other techniques that are either directly X-ray-related or come about as a secondary result of X-ray interaction with matter, such as X-ray photoemission spectroscopy (XPS), surface-extended X-ray absorption fine structure (SEXAFS) spectroscopy, Auger electron spectroscopy (AES), and time-resolved X-ray diffraction techniques, to name only a few [1,2]. 

Microwave Region Microwave spectroscopy and electron spin resonance (ESR) (due to absorption) are employed as analytical methods. 

To characterize dendrimers, analytical methods used in synthetic organic chemistry as well as in macromolecular chemistry can be applied. Mass spectrometry and NMR spectroscopy are especially useful tools to estimate purity and structural perfection. To get an idea of the size of dendrimers, direct visualization methods such as atomic force microscopy (AFM) and transmission electron microscopy (TEM), or indirect methods such as size exclusion chromatography (SEC) or viscosimetry, are valuable. Computer aided simulation also became a very useful tool not only for the simulation of the geometry of a distinct molecule, but also for the estimation of the dynamics in a dendritic system, especially concerning mobility, shape-persistence, and end-group disposition. 

Table 5.2 Summary of selected analytical methods for molecular environmental geochemistry. AAS Atomic absorption spectroscopy AFM Atomic force microscopy (also known as SFM) CT Computerized tomography EDS Energy dispersive spectrometry. EELS Electron energy loss spectroscopy EM Electron microscopy EPR Electron paramagnetic resonance (also known as ESR) ESR Electron spin resonance (also known as EPR) EXAFS Extended X-ray absorption fine structure FUR Fourier transform infrared FIR-TEM Fligh-resolution transmission electron microscopy ICP-AES Inductively-coupled plasma atomic emission spectrometry ICP-MS Inductively-coupled plasma mass spectrometry. Reproduced by permission of American Geophysical Union. O Day PA (1999) Molecular environmental geochemistry. Rev Geophysics 37 249-274. Copyright 1999 American Geophysical Union...

These analytical dilemmas interfere with the methods of alkaloid analysis. Each group of alkaloids has its own methods of extraction, isolation and crystallization, as well as detection in structure, molecule and dynamicity. Not all these stages are still possible in the majority of alkaloids. In recent years, many techniques have been used in alkaloid detection. There are atomic and molecular electronic spectroscopy, vibration spectroscopy and electron and nuclear spin orientation in magnetic fields, mass spectroscopy, chromatography, radioisotope and electrochemical techniques. Although important developments in methodology and... 

Although a number of secondary minerals have been predicted to form in weathered CCB materials, few have been positively identified by physical characterization methods. Secondary phases in CCB materials may be difficult or impossible to characterize due to their low abundance and small particle size. Conventional mineral identification methods such as X-ray diffraction (XRD) analysis fail to identify secondary phases that are less than 1-5% by weight of the CCB or are X-ray amorphous. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM), coupled with energy dispersive spectroscopy (EDS), can often identify phases not seen by XRD. Additional analytical methods used to characterize trace secondary phases include infrared (IR) spectroscopy, electron microprobe (EMP) analysis, differential thermal analysis (DTA), and various synchrotron radiation techniques (e.g., micro-XRD, X-ray absorption near-eidge spectroscopy [XANES], X-ray absorption fine-structure [XAFSJ). 

The most frequently applied analytical methods used for characterizing bulk and layered systems (wafers and layers for microelectronics see the example in the schematic on the right-hand side) are summarized in Figure 9.4. Besides mass spectrometric techniques there are a multitude of alternative powerful analytical techniques for characterizing such multi-layered systems. The analytical methods used for determining trace and ultratrace elements in, for example, high purity materials for microelectronic applications include AAS (atomic absorption spectrometry), XRF (X-ray fluorescence analysis), ICP-OES (optical emission spectroscopy with inductively coupled plasma), NAA (neutron activation analysis) and others. For the characterization of layered systems or for the determination of surface contamination, XPS (X-ray photon electron spectroscopy), SEM-EDX (secondary electron microscopy combined with energy disperse X-ray analysis) and... 

A number of reviews can be consulted for an introduction to the fundamentals both theoretical and practical covering XPS. These include Riggs and Parker (2) and the book by Carlson (3). Electron spectroscopy is reviewed in alternate years in the Fundamental Reviews issue of Analytical Chemistry. The last literature review was published in 1980 (4) and this and previous reviews can be consulted for a coverage of all aspects of the literature of XPS. A number of recent symposia have been held on applications of surface analytical methods in various aspects of materials science such as the symposium on characterization of molecular structures of polymers by photon, electron, and ion probes at the March 1980 American Chemical Society meetings in Houston ( 5) and the International Symposium on Physiochemical Aspects of Polymer Surfaces at this meeting as well as the symposium on industrial applications of surface analysis of which this article is a part. Review articles on various applications of XPS in materials science are listed in Table I. 

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