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X-ray spectroscopy Andrew Preston andrew@preston.co.nz
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Outline of proceedings 1.Synchrotrons 2.Beamlines 3.Advantages/Applications 4.How to get access
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1. Synchrotrons
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What is a synchrotron? A big circle… …which accelerates charged particles… …which radiate light… …which we use
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It’s a light source!
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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
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Uses Biosciences Medicine Environmental sciences Agriculture Minerals exploration Advanced materials Engineering Forensics
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Light sources around the world
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NSLS (New York)
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Maxlab (Sweden)
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Australian synchrotron
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Beamlines –Protein crystallograppy –Infrared spectroscopy –Soft x-ray spectroscopy –X-ray absorption spectroscopy –Powder diffraction
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Australian synchrotron Beamlines under construction –Small and wide angle scattering –Protein micro-crystal and small moleculte XRD –Microspectroscopy –Imaging and theray
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Experiment 2. Beamlines Light source Generate light (synchrotron) Isolate particular colour (monochromator) Conduct experiment
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3. Advantages
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Atom specific EfEf Empty Filled
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Very bright
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X-ray absorption XAS, XANES, NEXAFS, EXAFS Probe the unoccupied states around an atom
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XAS Band structure of ZnO from resonant x-ray emission spectroscopy Preston et al. Phys. Rev. B 78, 155114 (2008)
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EfEf XPS, ARPES Photoelectric effect Measure kinetic energy of emitted electrons Photoelectron spectroscopy Empty Filled
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XPS/ARPES Measure the total density of states around an atom Surface state effects ARPES –resolve momentum of emitted electrons
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ARPES Origin of the metallic properties of boron-doped diamond Yokoya et al. Nature 438, 647 (2005)
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X-ray diffraction Similar to conventional XRD High flux –Better signal:noise ration High resolution –Angle/time
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Highly oriented polythiophene thin-film transistors Kline et al. Nat. Mat. 5, 222 (2006)
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4. How to get access Apply! Apply!! Apply!!! New Zealand Synchrotron Group Ltd. –http://www.synchrotron.rsnz.org/user/http://www.synchrotron.rsnz.org/user/
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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!
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References Tour of the ALS –http://www.youtube.com/watch?v=iEHWQv7b-Cwhttp://www.youtube.com/watch?v=iEHWQv7b-Cw Light sources –http://www.lightsources.org/http://www.lightsources.org/ Australian synchrotron –http://www.synchrotron.org.auhttp://www.synchrotron.org.au New Zealand Synchrotron Group Ltd. –http://www.synchrotron.rsnz.org/http://www.synchrotron.rsnz.org/ X-ray data booklet –http://xdb.lbl.gov/http://xdb.lbl.gov/
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