XAFS Data Booklet Proposal

Raúl Barrea and Tsu-Chien Weng

BioCAT, IIT

03-22-2005

Why Another Booklet?

•Official guideline from IXS to standardize sample preparation, XAFS measurement, data analysis, and report format

•Educational purpose

•Advertisement for IXS and APS

Things to Discuss

•Booklet contents

•Contributors

•Funding

•Distribution

•Publishing timeline

Booklet Outline1. X-ray Properties of the Elements

2. XAFS Basics

3. Guideline for Sample Preparation

4. XAFS Experiments

5. Data Analysis

6. Report Format

7. XAFS Beamlines

1. X-ray Properties of the Elements

•X-ray absorption edge and emission energies

•Mass absorption coefficients

2. XAFS Basics

•History

•Theory

•EXAFS and XANES

•Capabilities and limitations

•Applications

3. Guideline for Sample

Preparation•Solid sample

– thickness (self-absorption)

– packing (pin hole effect)

•Solution sample

– contamination from free metal ions

– background from buffers (Cl, P, etc.)

•Drawing of sample cells

4. XAFS Experiments•X-ray optics

– high-order harmonics (detuned, rejection)

– energy calibration•Sample cell– cryostat, high-pressure, solution, etc.– radiation damage

•Detectors– absorption (ion-chamber, PSD)– fluorescence excitation (SSD, bent Laue,

MAAD, crystal mirror)– energy resolution, ICR

5. Data Analysis

•Energy calibration

•Background subtraction and normalization

•EXAFS data interpretation

– choice of model

– degree of freedom

6. Report Format•Experiment details– beamline(s), x-ray optics– means of energy calibration– sample preparation (thickness,

buffers)– fluorescence window size– scan time, count-rates

•Data analysis– threshold energy– degree of freedom vs. num of

variables– (reduced) goodness of fit

7. XAFS Beamlines

•Characteristics of each XAFS beamline

– source (BM, ID)

– energy range

– spot size (unfocused, focused)

– sample cell (cryostat, high-pressure, etc.)

– detector(s)

– specialties (time-resolved, RIXS, etc.)

Things to Discuss

•Booklet contents

•Contributors

•Funding (APS? DOE? Private companies?)

•Distribution (hardcopy, electronic)

•Publishing timeline (9-12 months?)