ZPEnergy.com - Physicists get ultra-sharp glimpse of electrons

In this image showing the energy levels of electrons in a two-dimensional system, the electrons can be thought of as a sea, filling all the lowest places available and with a surface at sea level. In the picture, the dark line across the center is the sea level. Bright lines show where the energy levels are. The distance of the lines from the sea level shows how large their energy is, with lines below the center showing states that are normally filled (underwater) and lines above the center showing states that are normally empty (up in the air). Tracing out the energy levels as the number of electrons in the system is changed, from left to right in the plot, scientists can learn how electrons behave together in large groups. Graphic courtesy / Ashoori Group Lab

Two-dimensional electron systems, in which electrons are walled in from above and below but are free to move in a plane as if they were placed on a sheet of paper, are rarely observed in the natural world. However, they can be created in a laboratory and used, for example, in high-frequency amplifiers found in cell phones.

The new spectroscopy technique measures electron energy levels with 1,000 times greater resolution than previous methods, an advance that has "tremendous power to tell you what the electrons are doing," said MIT physics professor Ray Ashoori, author of a paper on the work published in the July 12 issue of Nature. This technique has already revealed some surprising behavior, and the researchers believe it will shed new light on many physical phenomena involving electrons.

Ashoori and postdoctoral associate Oliver Dial took advantage of a quantum phenomenon known as tunneling to create the most detailed image ever of the spectrum of electron energy levels in a 2D system.

The new spectroscopy technique relies on a phenomenon that defies the laws of classical mechanics. Electrons, because they exhibit wavelike behavior, can move between two locations separated by a barrier without having to pass over the barrier--a phenomenon known as "quantum tunneling."

"We anticipate that this technique will help us discover all kinds of new physics," said Ashoori. "We're looking into a realm that was just not visible to us before."
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More: http://www.physorg.com/news104156028.html