| 书目名称 | NEXAFS Spectroscopy | | 编辑 | Joachim Stöhr | | 视频video | | | 丛书名称 | Springer Series in Surface Sciences | | 图书封面 |  | | 描述 | The purpose of this book is the development of the principles and experimental techniques underlying near edge X-ray absorption fine structure (NEXAFS) spectroscopy and the demonstration of the power of the technique for the study of the electronic and crystallographic structure of low-Z molecules bonded to surfaces. Low-Z molecules are defined as those consisting of hydrogen, carbon, nitrogen, oxygen and/or fluorine atoms, which are particularly important in surface chemistry. This book is the first comprehensive treatment of the subject and presents a unified picture of theoretical and experimental concepts and results. It develops all concepts from an elementary level and is suitable for students and researchers without extensive prior knowledge in X-ray absorption spectroscopy. On the other hand, it discusses state-of-the-art instrumentation, analysis techniques, and experimental and theoretical results and is therefore also suited for the advanced spectroscopist. The spectra of free molecules are discussed first, since their understanding provides the basis for understanding spectra of molecules bonded to surfaces, the main topic of the book. The connection to spectra of polym | | 出版日期 | Textbook 1992 | | 关键词 | Absorption; Adsorption; EXAFS; LED; NEXAFS; STEM; molecule | | 版次 | 1 | | doi | https://doi.org/10.1007/978-3-662-02853-7 | | isbn_softcover | 978-3-642-08113-2 | | isbn_ebook | 978-3-662-02853-7Series ISSN 0931-5195 Series E-ISSN 2198-4743 | | issn_series | 0931-5195 | | copyright | Springer-Verlag Berlin Heidelberg 1992 |
| 1 |
Front Matter |
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Abstract
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| 2 |
,Introduction, |
Joachim Stöhr |
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Abstract
In this first chapter we outline the reasons for writing a book about the near edge X-ray absorption fine structure, or NEXAFS, technique, and explain why the application of the technique to the study of molecules bonded to surfaces is particularly important and interesting. A historical perspective of the development of NEXAFS spectroscopy is also given.
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| 3 |
,Theory of Inner Shell Excitation Spectra, |
Joachim Stöhr |
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Abstract
Below we review the fundamental aspects underlying the calculation of X-ray absorption spectra. We emphasize approximations commonly made for the calculation of transition energies and transition intensities and, in particular, discuss two theoretical techniques which have been successfully applied for the calculation of molecular X-ray absorption spectra.
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| 4 |
,Symmetry and Molecular Orbitals, |
Joachim Stöhr |
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Abstract
In this chapter the rudiments of molecular orbital theory are reviewed in the light of their importance for the understanding of the resonances which dominate molecular X-ray absorption spectra. Particular emphasis is given to the symmetry classification of orbitals and how it relates to the polarization dependent dipole selection rule that governs X-ray absorption.
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| 5 |
,Experimental and Calculated ,-Shell Spectra of Simple Free Molecules, |
Joachim Stöhr |
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Abstract
Here an overview is given of the spectral features that are encountered in .-shell excitation spectra of simple gas phase molecules. Experimental results obtained by the inner shell electron energy loss, or ISEELS, technique — which is discussed first — are compared to those obtained by different theoretical techniques.
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| 6 |
,Principles, Techniques, and Instrumentation of NEXAFS, |
Joachim Stöhr |
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Abstract
In this chapter a basic question is addressed: How can the X-ray absorption signal from a single molecular layer on the surface of a bulk material be measured? In particular, electron yield and fluorescence yield detectors and experimental techniques are discussed and specific attention is given to the problems of normalization and background correction of experimental data.
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| 7 |
,Spectra of Condensed, Chemisorbed, and Polymeric Molecules: An Overview, |
Joachim Stöhr |
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Abstract
Here we show how the .-shell excitation spectra of simple free molecules, discussed in Chap. 4, evolve under the influence of extramolecular interactions in the form of van-der-Waals or chemical bonds at surfaces, and develop a molecular-orbital-based understanding of the systematic changes of the spectra with increasing molecular size.
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| 8 |
,Analysis of ,-Shell Excitation Spectra by Curve Fitting, |
Joachim Stöhr |
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Abstract
Below we review methods for the quantitative analysis of NEXAFS spectra. Theoretical expressions are given for the lineshapes of features, such as steps and peaks, that are commonly encountered in NEXAFS spectra. Also, we discuss general guidelines for the positions and shapes of characteristic features.
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| 9 |
,σ* Resonance Position and Bond Length, |
Joachim Stöhr |
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Abstract
In this chapter we review the evidence for a correlation between the σ* resonance position and the molecular bond length. In particular, we investigate the question of whether and how the correlation found for simple free molecules can be extended to large molecules and to physisorbed and chemisorbed molecules.
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| 10 |
,The Angular Dependence of Resonance Intensities, |
Joachim Stöhr |
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Abstract
Below we derive the theoretical expressions that govern the angular dependences of NEXAFS resonances in molecular adsorption systems, observed in polarization dependent studies. A simple, general classification of all molecular systems is given, and for these classes analytical expressions for the angle-dependent resonance intensities are derived, assuming that the X-rays are elliptically polarized.
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| 11 |
,Selected Applications of NEXAFS, |
Joachim Stöhr |
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Abstract
Here we discuss selected examples of how NEXAFS has been used to obtain information on the electronic and crystallographic structure of molecular adsorption systems. Our examples cover a wide range of molecular adsorption energies, from weak van-der-Waals like interactions to strong chemical bonds, and address a diversity of molecules, ranging from diatomics to larger rings and chains.
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| 12 |
,A Look into the Future, |
Joachim Stöhr |
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Abstract
With the availability of dedicated (second generation) synchrotron radiation sources around the world and suitable soft X-ray monochromators, such as the SX-700 plane grating [11.1, 2] or Dragon spherical grating [11.3, 4] instruments, conventional NEXAFS studies in the 1990s are limited neither by flux nor by resolution. Although many improvements in instrumentation are possible, to conclude this book we want to ask whether there are any truly novel and exciting opportunities on the horizon. In the following let us therefore do some brainstorming about possible future applications of NEXAFS spectroscopy. We shall restrict ourselves to novel ideas not mentioned in previous chapters. Most of these ideas are centered around new instrumentation in the form of new synchrotron radiation sources, novel monochromators or simply end-of-line equipment.
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| 13 |
Back Matter |
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Abstract
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发表于 2025-3-21 17:04:22
