News in Science

Cold electrons provide sharper focus

Cool nanotech Australian scientists have developed a new way of imaging atoms, which could lead to new types of drugs in medicine and a better understanding of materials for engineering.

Called a cold electron source, it will be capable of improving the quality and speed of nano-imaging.

The work reported this week in the journal Nature Physics will eventually allow scientists to watch how proteins react to different chemicals or how microscopic cracks propagate in the turbine blades of jet engines.

The research led by Associate Professor Robert Scholten from the University of Melbourne's School of Physics is designed to overcome problems conventional synchrotron x-rays and electron microscopes have in taking intricate images.

He says existing electron microscopes tend to scatter electrons like the indirect light of light bulbs rather than the sharp direct focus of a laser beam.

"It's a bit like steam coming out of a kettle, the steam goes everywhere, you can't really control it", says Scholten.

"But if you could control the electrons so they all fire as a beam in a straight line, you can work out what you're imaging far better."

"To do that, you have to keep the electrons very cold."

Laser beams

Scholten and colleagues did this by firing a series of laser beams into rubidium gas cooled to 70 millionths of a kelvin - close to absolute zero.

This process releases electrons slowly and allows them to control which part of the rubidium gas they target, producing specific shapes in the electron cloud that's released.

"Because the electrons are still extremely cold after they're knocked off the atom, just 10 Kelvin, they remain in whatever configuration you place them in," says Scholten.

The researchers then used an electric field to focuses the electrons onto a target.

According to Scholten, shaping the electron cloud is the only way to get enough electrons onto the target quickly enough to get the detailed image you're after.

The eventual goal, says Scholten, is to be able to create a movie of what's happening on the nano scale.