Introduction to XAFS: A Practical Guide to X-ray Absorption Fine Structure Spectroscopy Book

Preface vii

1 Introduction 1

1.1 What is XAFS? 1

1.2 Physics of XAFS 2

1.3 Synchrotron radiation 4

1.4 Purpose of this book 6

2 Basic physics of X-ray absorption and scattering 8

2.1 X-rays 8

2.2 The structure of atoms 9

2.3 Atomic units 11

2.4 Types of interactions 13

2.5 Cross sections 14

2.6 Elastic scattering from free electrons 20

2.7 Elastic scattering from electron distributions 21

2.8 Elastic scattering from atoms with no excitation 24

2.9 Elastic scattering from crystals 26

2.10 Fourier transform of the lattice 28

2.11 Compton scattering from free electrons 32

2.12 Inelastic scattering from atoms 32

2.13 Core-hole lifetime 33

3 Experimental 36

3.1 Requirements for XAFS experiments 36

3.2 X-ray sources 41

3.3 Synchrotron radiation 42

3.4 Beamlines and optics 52

3.5 X-ray detectors 60

3.6 XAFS experiments 80

3.7 Samples 96

3.8 Data acquisition 103

4 Theory 106

4.1 Introduction 106

4.2 Transition rate 107

4.3 Band structure, molecular orbital, clusters 115

4.4 Multiple scattering expansion 118

4.5 Outline of theoretical calculation 120

4.6 EXAFS equation 125

5 Data analysis 134

5.1 XANES 135

5.2 EXAFS 146

5.3 Data fitting 173

6 Related techniques and conclusion 189

6.1 Related techniques 189

6.2 Conclusion 191

Appendix 1 Introduction to Fourier transforms in EXAFS 193

Appendix 2 Cumulants in EXAFS 212

Appendix 3 Optimizing X-ray filters 219

Appendix 4 Reference spectra 232

Appendix 5 X-ray tables 241

References 251

Index 258