Physicist puzzle is superficial

SOMETIMES scratching the surface of a problem is still probing too deep.

In the laboratories of Murdoch University, Professor Steve Thurgate is tackling the delicate puzzle of surface physics – analysing the absolute outer layer of a material.

“Materials are often coated with a very thin layer of material that is different from the rest, and yet it is often this outermost layer that determines how the material will interact with the external environment.,” said Professor Thurgate.

“Scratching the surface to take a sample may give you an incorrect analysis of the material’s outer layer because we cannot take a sample that is thin enough.

“Therefore we are hunting for ways to test the external layer of materials with X-rays instead.”

Professor Thurgate’s particular method of surface analysis is called Auger Photoelectron Coincidence Spectroscopy (APECS), which involves exciting atoms with a dose of radiation and measuring the subsequent emission of electrons.

When radiated, each element produces electrons with a known energy, reflecting the atomic structure of that element.

Analysis of the energy of the electrons coming from the surface can be used to identify the elements present.

Professor Thurgate is working towards gaining a better understanding of the physics behind the emission processes.

This will not only demonstrate what elements are present, but also show how they are combined into different chemical species.

There are three teams in the world using APECS for surface analysis but Professor Thurgate is the only researcher to purpose-build instrumentation.

“By building a new type of equipment rather than relying on using a Synchrotron, we are able to better analyse a wider range of materials with much simpler equipment,” he said.

“We are far ahead of the other groups in terms of data rates, range of samples and number of samples analysed”

To date, Professor Thurgate has used funding from the Australian Research Council to determine why a range of metals including copper, silver, iron, tin, palladium, cobalt and nickel produce particular patterns of electron emission.

Working with collaborators around the world, Professor Thurgate is now starting to analyse lighter atoms such as oxygen, silicon and carbon, and is hoping to delve further into the analysis of polymers.

“Surface science plays an important role in a number of industries, primarily as a tool for failure analysis, new product development and research into new materials.” said Professor Thurgate.

“It is very important in the production of semi-conductor devices, photonic devices, and it has pioneered many of the advances in nanotechnology. Surface science remains at the forefront of research in many areas.”