Transcript et al. - Andrew Preston

X-ray spectroscopy
Andrew Preston
[email protected]
Outline of proceedings
1.
Synchrotrons
2.
Beamlines
3.
Advantages/Applications
4.
How to get access
1. Synchrotrons
What is a synchrotron?
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A big circle…
…which accelerates charged particles…
…which radiate light…
…which we use
It’s a light source!
A very useful light source
• Very bright
– Millions of times brighter than x-ray tubes
• Very colourful
– Energies from infrared to hard x-ray
• Highly polarized
– linear or circular
• Great time resolution
– Pulses of nanosecond duration
• Key point: new uses, improves other uses
Uses
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Biosciences
Medicine
Environmental sciences
Agriculture
Minerals exploration
Advanced materials
Engineering
Forensics
Light sources around the world
NSLS (New York)
Maxlab (Sweden)
Australian synchrotron
Australian synchrotron
• Beamlines
– Protein crystallograppy
– Infrared spectroscopy
– Soft x-ray spectroscopy
– X-ray absorption spectroscopy
– Powder diffraction
Australian synchrotron
• Beamlines under construction
– Small and wide angle scattering
– Protein micro-crystal and small moleculte
XRD
– Microspectroscopy
– Imaging and theray
2. Beamlines
• Generate light (synchrotron)
• Isolate particular colour (monochromator)
• Conduct experiment
Experiment
Light source
3. Advantages
Atom specific
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Very bright
X-ray absorption
• XAS, XANES, NEXAFS, EXAFS
• Probe the unoccupied states around an
atom
XAS
Band structure of ZnO from resonant x-ray emission spectroscopy
Preston et al. Phys. Rev. B 78, 155114 (2008)
Photoelectron spectroscopy
• XPS, ARPES
• Photoelectric effect
• Measure kinetic energy
of emitted electrons
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XPS/ARPES
• Measure the total density of states around
an atom
• Surface state effects
• ARPES
– resolve momentum of emitted electrons
ARPES
Origin of the metallic properties of boron-doped diamond
Yokoya et al. Nature 438, 647 (2005)
X-ray diffraction
• Similar to conventional XRD
• High flux
– Better signal:noise ration
• High resolution
– Angle/time
Highly oriented polythiophene thin-film transistors
Kline et al. Nat. Mat. 5, 222 (2006)
4. How to get access
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Apply!
Apply!!
Apply!!!
New Zealand Synchrotron Group Ltd.
– http://www.synchrotron.rsnz.org/user/
New Zealand Synchrotron Group
• Your university is a shareholder
• Designed to encourage use
• Two types of access
– Merit (50%)
– Preferred (30%)
• Can you apply?
– YES!
References
• Tour of the ALS
– http://www.youtube.com/watch?v=iEHWQv7b-Cw
• Light sources
– http://www.lightsources.org/
• Australian synchrotron
– http://www.synchrotron.org.au
• New Zealand Synchrotron Group Ltd.
– http://www.synchrotron.rsnz.org/
• X-ray data booklet
– http://xdb.lbl.gov/