X-ray photoelectron spectroscopy ESCA

Of course, 57 must lie on the reaction path connecting the two open ions, but it is evidently a transition state and not an intermediate. However, evidence from x-ray photoelectron spectroscopy (ESCA) has shown that the 2-butyl cation is substantially methyl bridged.172... 

Chemical Labels to Distinguish Surface Functional Groups Using X-Ray Photoelectron Spectroscopy (ESCA)... 

The organic dielectrics known as polyimides have been studied extensively by a variety of bulk characterizational techniques as a perusal of the literature will illustrate. Little has been published on their surface properties. X-ray photoelectron spectroscopy (ESCA) has been extremely useful for polymer characterization (, 7, ), In a previous paper ( ), we have reported the ESCA spectra of structurally different polyimides derived from both commercially available polyamic acid resins (DuPont s PI5878, PI2525, PI2550), and from laboratory synthesized polyamic acid resins. 

The surface chemical structure of several thin polyimide films formed by curing of polyamic acid resins was studied using X-ray photoelectron spectroscopy (ESCA or XPS). The surface modifications of one of the polymer systems after exposure to KOH, after exposure to temperature and humidity, after exposure to boiling water, and after exposure to O2 and 02/CF plasmas were also evaluated. The results showed imide bond formation for all cured polyimide systems. It was found that (a) K on the surface of the polyamic acid alters the "normal" imidization process, (b) cured polyimide surfaces are not invarient after T H and boiling water exposures, and (c) extensive modifications of cured polyimide surfaces occur after exposures to plasma environments. Very complex surfaces for these polymer films were illustrated by the C Is, 0 Is, N Is and F Is line characteristics. 

An Arrhenius plot of the deposition rate vs reciprocal absolute temperature is shown in Fig. 2. Depositions were made by indicated pressures with or without carrier gas. One notices in all cases that above 190 °C the deposition rate of several A/s was found with an activation energy of about 50-60 kJ mol". Below this temperature a strong decrease of the deposition rate was found. It did not matter whether the gas phase consisted of pure precursor or of a mixture of organometallic compound and argon carrier gas. Only the value of the deposition rate was varying with the different pressures which can be explained by the amount of precursor in the gas phase. Similar results (Fig. 3) were also obtained with in situ X-ray photoelectron spectroscopy (ESCA) studies, which indicate a sharp shift of the binding energy as an onset of the start of decomposition of the precusor at around 190 °C. 

The surface properties of ACFs were measured by XPS (X-ray photoelectron spectroscopy, ESCA LAB MKII). The XPS was collected using a MgKa X-ray source (1253.6 eV). The pressure inside the chamber was held below 1X10 torr. 

X-ray photoelectron spectroscopy (ESCA) can be use to determine the chemical composition of the nanoparticle surface. This technique is a very useful tool for the development of surface modified nanoparticles providing a direct evidence of the presence of the components that are believed to be on the nanoparticle surface. ... 

G. Mende, J. Finster, D. Flamm, and D. Schulze, Oxidation of etched silicon in air at Room temperature Measurements with ultrasoft X-ray photoelectron spectroscopy (ESCA) and neutron activation analysis, Surf. Sci. 128, p. 169, 1983. 

Co—MoSj, by impregnating MoSj with Co, text p. 191). Abbreviations XRD, X-ray diffraction EM, electron microscopy EPMA, electron probe microanalysis XPS, X-ray photoelectron spectroscopy (ESCA) R, Raman DRS, UV-visible diffuse reflectance spectroscopy MOS,... 

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. 

Acronyms XPS or XPES X-ray photoelectron spectroscopy, ESCA electron spectroscopy for chemical apphcations (originally analysis), PESIS photoelectron spectroscopy of inner shell, ARXPS angle resolved X-ray photoelectron spectroscopy. 

In another approach. Holmes and Thomas measured the core binding energies of the nuclei in trifluoromethylbenzene, 1,3- and 1,4-di(trifluo-romethyl)benzene by X-ray photoelectron spectroscopy (esca) in the vapor phase to assess the charge distribution (45). Clark and his associates had previously described the esca spectrum of trifluoromethylbenzene in condensed phase (46). Their analysis of the poorly resolved signals of the aromatic carbon atoms re-... 

The importance of strong specific interactions in polymer adhesion (eg., covalent bonding, acid-base interaction) is well-known. However, these interactions are difficult to study directly, particularly for multifunctional surfaces. Derivatisation techniques have been developed which allow X-ray photoelectron spectroscopy (ESCA) to quantify functional group populations and to assess the success of specific modification techniques. Derivatised surfaces can then be used to study the role of specific interactions. 

Solid-state NMR (using cross-polarization magic-angle spinning techniques), isotopic substitution, and faster methods such as infrared, Raman, and, especially. X-ray photoelectron spectroscopy (ESCA) are particularly useful in investigating these systems. Some typical examples are depicted in Fig. 3. 

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. 

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