ESCA—See X-ray photoelectron

X-rays provide an important suite of methods for nondestmctive quantitative spectrochemical analysis for elements of atomic number Z > 12. Spectroscopy iavolving x-ray absorption and emission (269—273) is discussed hereia. X-ray diffraction and electron spectroscopies such as Auger and electron spectroscopy for chemical analysis (esca) or x-ray photoelectron spectroscopy are discussed elsewhere (see X-raytechnology). 

Microanalytical methods are used to move further down in the characterization scale. X-ray photoelectron spectroscopy (XPS or ESCA), (see Barr) Auger electron spectroscopy (AES), and secondary ion mass spectroscopy (SIMS) as presented by Leta for imaging FCC catalysts, are surface analysis techniques providing chemical analy-... 

An exciting development during this period was the ultraviolet photoelectron spectrometer invented by David W. Turner (1927- ) at Oxford in 1962. While X-ray photoelectron spectroscopy (ESCA) (see chapter 6) provides energies of core (e.g., Is) orbitals, UV photoelectron spectroscopy (UV PES) yields energies of valence-level MOs from the HOMO downward. The shapes of the UV PES bands also provide information about the nature of the orbitals. UV PES helped to improve computational theory and as computations improved they helped chemists pull more detail from UV PES data. 

For a brief description of the history of XPS. see K. Siegbahn. Science, 1981217. m D, M Hercules, / Chem. Educ.,Zm,81.1751. For mono-graphs, see S. HUfner. Photoelectron Spectroscopy Principles and Applications, Berlin Springer-Verlag, 1995 T. L. Barr. Modern ESCA The Principles and Practice of X-Ray Photoelectron Spectroscopy. Boca Raton, FLCRC Press. 1994,... 

Another important method for characterizing polymer surfaces involves electron spectroscopy for chemical analysis, ESCA, also known as X-ray photoelectron spectroscopy (XPS) see Table 12.3. This method is based on the observation that electrons are emitted by atoms under X-ray irradiation. The... 

The development of better analytical tools in recent years has enabled durability investigators to better understand that these specially prepared surfaces have unique surface geometries which can mechanically interact with the adhesive as well as provide a readily wettable surface. For many years the surfaces of metals were studied by electron microscopy, scanning electron microscopy, and electron diffraction techniques. Today these techniques have been supplemented by Auger electron spectroscopy (AES), electron spectroscopy for chemical analysis (ESCA), secondary ion mass spectroscopy (SIMS), X-ray emission spectroscopy (XES), X-ray photoelectron spectroscopy (XPS), and high-resolution scanning electron microscopy (XSEM). For more details the reader is referred to articles on the subject by Buckley( 3) and Davis and Venables.(54) (See also Chapters 6 and 7.)... 

X-Ray photoelectron spectroscopy (XPS) or ESCA is another routine analytical technique whose application to CPs is best illustrated by examples. Wide-spectrum XPS is a simple tool for elemental analysis, useful, e.g., to see the presence of an atom belonging to a particular dopant to verify doping. Higher resolution (core-level) XPS is typically useful for determining oxidation states of a central heteroatom, e.g. the N-atom in poly(aromatic amines), hence elucidating the redox state of the polymer or at least of the central heteroatom. Finally, valence-level spectra, at very low energies, have been said to be usable for estimation of density of states, although their accuracy is questionable. 

Since electron spectroscopy reached high precision, that is since the birth and development of ESCA (as described in [5]), the kinetic energy of electrons ejected from atoms can be directly measured. X-ray photoelectron spectroscopy (XPS) competes with X-ray spectroscopy to give electron binding energies. The work function of the electron spectrometer with which the test sample is in contact needs to be known. At present a reference value of a metal level, usually Au 4f7/2 (taken as 84.00 eV) is used. This technique is preferred especially for low-energy levels since X-ray transition measurements suffer from the addition of two experimental errors. Other techniques are also used such as isochromats (see [14]) or appearance potential observations, and Auger electron spectroscopy (AES) but this involves three levels. 

Soil retardants can be applied to fibers, yams, fabrics, or carpets by spraying, padding, kiss-roll, or foam application techniques. Some soil retardants are applicable also by exhaust methods. Spraying is the most popular method for applying soil retardants to carpets. The required amount of a soil-retardant product is typically 0.5-1.6% of the weight of dry face fiber or about 200 ppm as fluorine. Usually, the soil retardant as applied as the last step before the carpet is dried. The presence of a fluorinated finish on the carpet can be confirmed by an oil-repel-lency test, based on the AATCC 118-1997 test (see Chapter 12), or a water-repel-lency test. Fuorier transform infrared and x-ray photoelectron spectroscopy (ESCA) (Chapter 9) provide semiquantitative information on the fluorinated soil-retardant concentration on the fibers. 

As the X-ray photoelectron spectroscopy technique is very surface sensitive, the fluoropolymers were carefully transferred - through the air - from the sputtering vessel to the ESCA spectrometer, and analyzed without further chemical or mechanical treatment. All the studied samples were stable in air (see below) and in the spectrometer during the analysis, i.e. no degradation could be detected. 

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