New Scientist, written in cold electrons

Wendy Zukerman, reporter

(Image: University of Melbourne)

This spooky version of the New Scientist logo is one of the first images to be created using extremely cold electrons.

It's more than just a bit of fun. Cold electron microscopy could be used to create movies of tiny, fast-moving objects such as morphing proteins.

Typically electron microscopes use beams of hot electrons. As electrons have a much smaller wavelength than photons, they can image the micro- and nano-world. The downside is that hot electrons travel in random directions, so very few make it to the microscope's detector.

As a result, electron microscopes can take days to image an object, making it tough to capture a moving target such as a functioning protein.

But cold electrons don't diffuse as quickly, which should allow researchers to focus them on one target, producing images much brighter than those of typical electron microscopes.

This in turn raises the prospect of much faster imaging. "Bright means fast," explains Robert Scholten of the University of Melbourne in Australia. He hopes to image proteins as they change their shape in response to their environment, which will help design drugs that either block or enhance a protein's function.

To create the image above (at our behest), Scholten and his team cooled rubidium atoms to a few millionths of a degree above absolute zero using a laser. With a second laser they traced the New Scientist logo over the cold atoms, which excited them in the pattern of the logo.

A pulse of light from a third laser then forced only these excited atoms to release electrons, which were propelled by an electric field towards a detector. Since they were cold, they stayed in the shape of the logo for 20 nanoseconds, enough time for Scholten to snap up this image. "It's a very long time for electrons to keep their shape," he says.

The technique could "revolutionise the study of biological material", says John Terlet at the University of Adelaide, Australia who was not involved in the study.

"This is very clever bit of physics," says Simon Ringer at the University of Sydney, Australia. "They have created a different kind of light bulb."?

In 2008 Ahmed Zewail, a chemist at the California Institute of Technology in Pasadena, used fast, short electron pulses that acted like a strobe light to produce high-resolution footage of atoms in motion.

Journal reference: Nature Physics, DOI: 10.1038/NPHYS2052

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