XAFS for Everyone provides a practical, thorough guide to x-ray absorption fine-structure (XAFS) spectroscopy for both novices and seasoned practitioners from a range of disciplines. The text is enhanced with more than 200 figures as well as cartoon characters who offer informative commentary on the different approaches used in XAFS spectroscopy.
The book covers sample preparation, data reduction, tips and tricks for data collection, fingerprinting, linear combination analysis, principal component analysis, and modeling using theoretical standards. It describes both near-edge (XANES) and extended (EXAFS) applications in detail. Examples throughout the text are drawn from diverse areas, including materials science, environmental science, structural biology, catalysis, nanoscience, chemistry, art, and archaeology. In addition, five case studies from the literature demonstrate the use of XAFS principles and analysis in practice. The text includes derivations and sample calculations to foster a deeper comprehension of the results.
Whether you are encountering this technique for the first time or looking to hone your craft, this innovative and engaging book gives you insight on implementing XAFS spectroscopy and interpreting XAFS experiments and results. It helps you understand real-world trade-offs and the reasons behind common rules of thumb.
Table of Contents
The XAFS Experiment
XAFS in a Nutshell
X-Ray Absorption Spectra
Basics of EXAFS Theory
XAFS Is Not a Black Box
Overview of Approaches to XAFS
Planning the Experiment
Identifying Your Questions
Synchrotron Light Sources
Bending Magnets and Insertion Devices
Monochromators (and Polychromators)
Measurement Modes and Detectors
Sample Characteristics for Transmission
Sample Characteristics for Fluorescence
Sample Considerations for Electron Yield Experiments
Which Technique Should You Choose?
Calibration and Alignment
Finding Normalized Absorption
Finding the Fourier Transform
Noise, Distortion, and Time
Before You Begin
Optimizing the Beam
Suppressing Fluorescent Background
Aligning the Sample
Matching Empirical Standards
Fingerprinting Spectral Features
Theoretical XANES Standards
Linear Combination Analysis
When LCA Works
When LCA Doesn’t Work
An Example of LCA
Statistics of Linear Combination Fitting
Sources of Systematic Error
Choosing Data Range and Space for LCA
Principal Component Analysis
The Idea of PCA
How Many Components?
How Many Constituents?
PCA of EXAFS
How PCA Is Used
Curve Fitting to Theoretical Standards
The Path Expansion
A Dictionary of Parameters
Common Fitting Parameters
Less Common Fitting Parameters
Identifying a Good Fit
Criterion 1: Statistical Quality
Criterion 2: Closeness of Fit
Criterion 3: Precision
Criterion 4: Size of Data Ranges
Criterion 5: Agreement outside the Fitted Range
Criterion 6: Stability
Criterion 7: Are the Results Physically Possible?
Criterion 8: How Defensible Is the Model?
Evaluating a Fit
The Process of Fitting
Identify Your Questions
Prepare Your Data
Plan Your Strategy
Inequivalent Absorbing Sites
Constraints Based on a Priori Knowledge
Constraints for Simplification
Some Special Cases
Alternatives for Incorporating a Priori Knowledge
XAFS in the Literature
Know Your Audience
Models and Standards
Introduction to the Case Studies
Lead Titanate, a Ferroelectric
An Iron–Molybdenum Cofactor Precursor
Manganese Zinc Ferrite, an Example of Fitting Site Occupancy
Sulfur XANES from the Wreck of the Mary Rose
Identification of Manganese-Based Particulates in Automobile Exhaust
The Next Case Study: Yours
References appear at the end of each chapter.
Scott Calvin is the chair of the Division of Natural Science and Mathematics at Sarah Lawrence College, where he teaches innovative courses, including crazy ideas in physics, rocket science, and steampunk physics. He is also a member of the principal research team for beamline X-11B at the National Synchrotron Light Source. Since 1998, he has been using XAFS to study systems as diverse as solar cells, magnetic nanoparticles, soil samples, battery cathodes, analogues to atmospheric dust particles, and pigments used in 18th century painting. He received a PhD in physics from Hunter College of the City University of New York.
"The book is very timely … It is unique in covering theoretical background and experimental details to data analysis in a way that is easy to understand. It will be very valuable to anyone who is interested in using x-ray spectroscopy by helping them to better design and get more out of their experiments."
—Dr. Chi-Chang Kao, Director, SLAC National Accelerator Laboratory
"The author has found fun and engaging ways to explain details of XAFS that otherwise can seem so dry. I am sure that folks who use my beamline and software will love XAFS for Everyone."
—Dr. Bruce Ravel, National Institute of Standards and Technology
"A unique presentation with great value for readers and special emphasis on practical aspects … a ‘must have’ for XAFS scientists and beamlines."
—Prof. Mark C. Ridgway, Department of Electronic Materials Engineering, Australian National University
"This book will be useful to graduate students, post docs, and researchers. I highly recommend it."
—Dr. Richard W. Strange, Molecular Biophysics, The University of Liverpool