X-ray spectroscopy Andrew Preston

Outline of proceedings 1.Synchrotrons 2.Beamlines 3.Advantages/Applications 4.How to get access

1. Synchrotrons

What is a synchrotron? 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 Biosciences Medicine Environmental sciences Agriculture Minerals exploration Advanced materials Engineering Forensics

Light sources around the world

NSLS (New York)

Maxlab (Sweden)

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

Experiment 2. Beamlines Light source Generate light (synchrotron) Isolate particular colour (monochromator) Conduct experiment

3. Advantages

Atom specific EfEf Empty Filled

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, (2008)

EfEf XPS, ARPES Photoelectric effect Measure kinetic energy of emitted electrons Photoelectron spectroscopy Empty Filled

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 Apply! Apply!! Apply!!! New Zealand Synchrotron Group Ltd. –

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 – Light sources – Australian synchrotron – New Zealand Synchrotron Group Ltd. – X-ray data booklet –