x-ray spectroscopy

X-ray spectroscopy

Andrew Preston

andrew@preston.co.nz

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

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

Ef

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, 155114 (2008)

Ef

• 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.– 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/