Ultrafast imaging of electron waves in graphene

Celia Elliott
11/5/2010 12:00 AM

The fastest movies ever made of electron motion, created by scattering x-rays off of graphene, have shown that the interaction among its electrons is surprisingly weak.

Graphene is a single atomic layer of carbon whose unusual electronic structure makes it a candidate for a new generation of low-cost, flexible electronics. A major outstanding question is whether the electrons in graphene move independently, or if their motion is correlated by Coulomb repulsion.

Using advanced x-ray scattering techniques, physicists in Peter Abbamonte’s group at the University of Illinois at Urbana-Champaign have imaged the motion of electrons in graphene with resolutions of 0.533 Å and 10.3 attoseconds. Their results were published on November 5 in Science.

Exactly how small and how fast are these measurements? An angstrom is 1/10,000,000,000 of a meter, about the width of a hydrogen atom. And an attosecond is to a second as a second is to the age of the universe.

The researchers found that graphene screens Coulomb interactions surprisingly effectively, causing it to act like a simple, independent-electron semimetal. Their work explains several mysteries, including why freestanding graphene fails to become an insulator as predicted. The study also demonstrates a new approach to studying ultrafast dynamics, creating a new window on the most fundamental properties of materials.

The experiments were carried out at the Frederick Seitz Materials Research Laboratory at the University of Illinois and the Advanced Photon Source at Argonne National Laboratory.

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SAVOY, ILL - Pulling a tablecloth off of a table filled with dishes or riding around on a fire-extinguisher powered scooter may not seem like activities that teach the fundamentals of science. However, one program that has existed in Central Illinois for nearly 25 years has been doing just that. The University of Illinois Physics Van program teaches students from Kindergarten through 6th grade all about science in a fun and interactive way. 

"The larger the word you use when explaining something you start to lose kids interest. You have to show things on a really life sized level." says Brian Korn, Coordinator of the Physics Van 

The Physics Van presents a variety of programs to students, including teaching the principals of electricity and the laws of gravity.