Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

MIT physicists get ultra-sharp glimpse of electrons

24.07.2007
MIT physicists have developed a spectroscopy technique that allows researchers to inspect the world of electrons confined to a two-dimensional plane more clearly than ever before.

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."

Electrons trapped in 2D systems exist in specific energy levels, just as electrons orbiting an atom's nucleus in three dimensions exist in distinct quantum energy levels. By measuring which energy levels are occupied, physicists can study how electrons behave together in large groups.

The researchers used short pulses of electricity to induce electrons to tunnel from a 2D system to a 3D system, and vice versa. By measuring the resulting voltage difference, they could calculate the energy states of the electrons in the 2D system.

The spectroscopy experiments were performed inside a semiconducting crystal cooled to 0.1 degrees above absolute zero.

Until now, the primary method for performing this kind of spectroscopy relied on photoemission. The new method has an energy resolution that is 1,000 times finer than the best photoemission measurements.

Physicists have also traditionally used "transport" techniques that measure electrical currents flowing in response to applied voltages to learn about 2D electron energy levels, but that technique only offers a partial look at what electrons are doing.

"Similar to creating small ripples on the surface of a sea, transport techniques only tell us about what is happening very close to the water's surface," said Dial. "Pictures made with this high-resolution spectroscopy provide, in essence, one of the first glimpses of the entire ocean in these systems and show what a beautiful and interesting world exists beneath the surface."

The research was conducted in collaboration with crystal growers at Alcatel-Lucent Bell Laboratories in Murray Hill, N.J., and funded by the Office of Naval Research and the National Science Foundation.

Elizabeth A. Thomson | MIT News Office
Further information:
http://www.mit.edu

More articles from Physics and Astronomy:

nachricht When fluid flows almost as fast as light -- with quantum rotation
22.06.2018 | The Henryk Niewodniczanski Institute of Nuclear Physics Polish Academy of Sciences

nachricht Thermal Radiation from Tiny Particles
22.06.2018 | Universität Greifswald

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Temperature-controlled fiber-optic light source with liquid core

In a recent publication in the renowned journal Optica, scientists of Leibniz-Institute of Photonic Technology (Leibniz IPHT) in Jena showed that they can accurately control the optical properties of liquid-core fiber lasers and therefore their spectral band width by temperature and pressure tuning.

Already last year, the researchers provided experimental proof of a new dynamic of hybrid solitons– temporally and spectrally stationary light waves resulting...

Im Focus: Overdosing on Calcium

Nano crystals impact stem cell fate during bone formation

Scientists from the University of Freiburg and the University of Basel identified a master regulator for bone regeneration. Prasad Shastri, Professor of...

Im Focus: AchemAsia 2019 will take place in Shanghai

Moving into its fourth decade, AchemAsia is setting out for new horizons: The International Expo and Innovation Forum for Sustainable Chemical Production will take place from 21-23 May 2019 in Shanghai, China. With an updated event profile, the eleventh edition focusses on topics that are especially relevant for the Chinese process industry, putting a strong emphasis on sustainability and innovation.

Founded in 1989 as a spin-off of ACHEMA to cater to the needs of China’s then developing industry, AchemAsia has since grown into a platform where the latest...

Im Focus: First real-time test of Li-Fi utilization for the industrial Internet of Things

The BMBF-funded OWICELLS project was successfully completed with a final presentation at the BMW plant in Munich. The presentation demonstrated a Li-Fi communication with a mobile robot, while the robot carried out usual production processes (welding, moving and testing parts) in a 5x5m² production cell. The robust, optical wireless transmission is based on spatial diversity; in other words, data is sent and received simultaneously by several LEDs and several photodiodes. The system can transmit data at more than 100 Mbit/s and five milliseconds latency.

Modern production technologies in the automobile industry must become more flexible in order to fulfil individual customer requirements.

Im Focus: Sharp images with flexible fibers

An international team of scientists has discovered a new way to transfer image information through multimodal fibers with almost no distortion - even if the fiber is bent. The results of the study, to which scientist from the Leibniz-Institute of Photonic Technology Jena (Leibniz IPHT) contributed, were published on 6thJune in the highly-cited journal Physical Review Letters.

Endoscopes allow doctors to see into a patient’s body like through a keyhole. Typically, the images are transmitted via a bundle of several hundreds of optical...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Munich conference on asteroid detection, tracking and defense

13.06.2018 | Event News

2nd International Baltic Earth Conference in Denmark: “The Baltic Sea region in Transition”

08.06.2018 | Event News

ISEKI_Food 2018: Conference with Holistic View of Food Production

05.06.2018 | Event News

 
Latest News

Graphene assembled film shows higher thermal conductivity than graphite film

22.06.2018 | Materials Sciences

Fast rising bedrock below West Antarctica reveals an extremely fluid Earth mantle

22.06.2018 | Earth Sciences

Zebrafish's near 360 degree UV-vision knocks stripes off Google Street View

22.06.2018 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>