Photoelectron Spectroscopy and Diffraction

Further development of photoelectron spectroscopy as a tool for surface studies had to await important theoretical advances in atomic and sohd state physics brought about by the apphcation of quantum mechanics, and also by the advent of ultrahigh vacuum technology, suitable monochromatic photon sources, and 

Surface and Interface Science Concept and Me wds, First Edition. Edited by Klaus Wandelt 

In the intrinsic part of the photoemission spectrum, that is, the elastic lines, there are basically three observables associated with each core-level or valence band peak line positions, line intensities, and line widths or line shapes. From these, different pieces of information can be gained. In core-level emission, the rough line positions reveal the elemental composition of the sample surface, whereas the exact positions are characteristic of the specific chemical environment of the atoms [6j. The intensities are determined not only by the atomic concentrations but also by the photoelectric cross sections and instrumental effects such as the photon flux and the transmission of the spectrometer. Finally, information on the many-body dynamics of the solid after the sudden creation of a photohole (the missing electron that has been ejected) is contained in the shape and width of the peak. In the simplest case, the line shape is Lorentzian and its width is a measure of 

The above discussion also holds for valence band emission, with the exception of the line positions. In angle-resolved photoemission spectra, the peak positions move on the energy scale when the emission direction relative to the crystal axes is varied. From this peak dispersion, the energy versus momentum relation e k) of the solid bulk or surface can be deduced by simple kinematical arguments (Section 3.2.2.4.2). 

The measured photoemission intensity I( f) of a core-level peak at a kinetic energy in vacuum CHn = cf — 4 is related to the photoelectric cross section by the equation 

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X-ray Diffraction, X-ray Photoelectron Spectroscopy, and XAFS Spectroscopy Study 741... 

Laplante, F., Bernard, N., Tavares, A., Trasatti, S. and Guay, D. (2006) X-ray photoelectron spectroscopy and X-ray diffraction characterization of rhodium oxides in reductive conditions, in Electrocatalysis, Vol. 2005-11 (eds G.M. Brisard, R. Adzic, V. Birss and A. Wieckowski), The Electrochemical Society, Pennington, NJ. 

Other techniques previously described for general investigation of tautomeric equilibria (76AHC(S1)1> involve heats of combustion, relaxation times, polarography, refractive index, molar refractivity, optical rotation, X-ray diffraction, electron diffraction, neutron diffraction, Raman, fluorescence, phosphorescence and photoelectron spectroscopy, and mass spectrometry. The application of several of these techniques to tautomeric studies has been discussed in previous sections. Other results from the more important of these will be referred to later in this section. 

The results of theoretical methods are surveyed, followed by data on molecular dimensions obtained from X-ray diffraction or microwave spectroscopy. The results of NMR spectroscopy, including 1H, 13C, 14N, and 15N NMR, are then surveyed. This is followed by a discussion of UV, visible, IR, and photoelectron spectroscopy and mass spectrometry. Each of the spectroscopic sections deals with both the parent rings and the effects of substituents. 

Lince, J.R., Hilton, M.R. and Bommannavar, A.S., Oxygen Substitution in Sputter Deposited M0S2 Films Studied by Extended X-Ray Absorption Fine-Structure, X-Ray Photoelectron Spectroscopy and X-Ray Diffraction, Surf. Coat. Technol., 43/44, 640, (1990). 

The structure of the indium phospholyl [In( -P2C3-/-Bu3)] 39 was studied by X-ray diffraction, photoelectron spectroscopy, and using DFT <19990M793, 2000JCD1715>. 

Oxide nanopartides, unlike nanopartides of metals, display an expansion in their lattice parameters in comparison with the bulk. Tsunekawa et al. have examined sub-10 nm Ce02 and sub-100 nm BaTi03 nanopartides using a combination of electron diffraction, X-ray photoelectron spectroscopy and ab initio computer simulations. They find that in the Ce02 system, the lattice expansion arises from a decrease in Ce valence, whilst in the BaTi03 system, the decreasing Ti-0 covalency with decreasing particle size results in the expanded lattice. 

Structural and Surface Characterization of Carbon Products. Carbon products of the process were analyzed by a number of material characterization techniques, including x-ray diffraction, scanning electron microscopy. Auger electron spectroscopy, x-ray photoelectron spectroscopy, and others. X-ray diffraction studies revealed an ordered graphite-like (or turbostratic) structure of carbon products (Figure 4). 

The AlTUD-1 and the modified sample obtained after the immobilization process were characterized by surface analysis (X-ray photoelectron spectroscopy and powder X-ray diffraction), chemical analysis and adsorption of nitrogen at low temperature. 

Decomposition as discussed in this section has been studied by optical methods, X-ray diffraction, X-ray photoelectron spectroscopy, and infrared absorption. Although this section is concerned to a large extent with disorder resulting from decomposition of the metal sublattice, i.e., metal colloids, all types of disorder remaining after irradiation are considered, and some attention is given to the decomposition of the anion sub lattice. The decomposition of the anion sublattice of small band gap azides is considered in much greater detail in Section E dealing with gas evolution (primarily N2). 

The average size of magnetite and hydroxyapatite crystallites was calculated in accordance to (311) and (002) X-ray diffraction peaks, respectively, with the use of the Scherrer formula. The thickness of the hydroxyapatite layer on the surface of magnetite nanoparticles was 4 nm, which was evaluated by the area ratio of Fe2p- and Fe3p-lines (studied by X-ray photoelectronic spectroscopy) and the increase in the Fe304/HA nanocomposite mass ( 30%). 

All experimental methods for the determination of quantitative structural data of free molecules have been considered microwave, infrared, Raman, electronic and photoelectron spectroscopy and related spectroscopic methods as well as electron diffraction. All data obtained by these methods have been critically evaluated and compiled. The data are presented separately for each molecule, together with original references and in many cases with computer-drawn figure(s) carefully prepared by Dr. N. Vogt. 

Lamouri A, Gofer Y, Luo Y, Chottiner GS, Scherson DA. Low energy electron diffraction. X-ray photoelectron spectroscopy, and CO-temperature-programmed desorption characterization of bimetallic mtheninm-platinum surfaces prepared by chemical vapor deposition. J Phys Chem B 2001 105 6172-7. 

Chapter 4 is new to the fourth edition and pulls together the experimental techniques that previously were scattered through the book in themed boxes. The inclusion of a large number of worked examples, self-study exercises and end-of-chapter problems in this chapter benefits students and teachers alike, and also ensures that the text can support inorganic practical classes in addition to lecture courses. The techniques covered in Chapter 4 include vibrational, electronic, NMR, EPR, Mossbauer and photoelectron spectroscopies and mass spectrometry in addition to purification methods, elemental analysis, thermogravi-metric analysis, diffraction methods and computational methods. The practical issues of IR spectroscopy detailed in Chapter 4 complement the group theory approach in Chapter 3. 

In the case of new IP materials, standard chemical analysis techniques, such as infinred spectroscopy, nuclear magnetic resonance. X-ray photoelectron spectroscopy, and X-ray diffraction analysis, and thermogravimetric analysis and/or standard structural analysis methods, such as scatming electron microscopy (SEM), transmission electron microscopy (TEM), and atomic force microscopy (AFM), are used. 

Dimensional, morphological and chemical characterization of the ingredients, with particular attention to the metallic nano-powders and the combustion residuals, by means of electron microscopy (SEM, TEM, HRTEM), XPS (X-ray photoelectron spectroscopy) and XRD (X-ray diffraction). 

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