U.S. physicists reveal secrets of newest form of carbon

WASHINGTON, June 10 (Xinhua) -- A group of U.S. physicists have uncovered new secrets about the properties of graphene -- a newest form of pure carbon that may one day replace the silicon in computers, televisions, mobile phones and other common electronic devices.

Graphene is a single layer of carbon atoms arranged in a honeycombed lattice. Using one of the world's most powerful sources of man-made radiation, the group reported in this week's advance online publication of the journal Nature-Physics that their measurement shows the electrons in graphene strongly interact not only with the honeycomb lattice, but also with each other.

Graphene has a number of advantages over silicon. Because it is an optically transparent conductor of electricity, graphene could be used to replace current liquid crystal displays that employ thin metal-oxide films based on indium, a rare metal that is becoming increasingly expensive and likely to be in short supply within a decade.

The problem for scientists is that not much is known about its optical and electronic properties because graphene, which was discovered only four years ago, has resisted traditional forms of spectroscopy.

The physicists report that they used the Advanced Light Source (ALS) at the Lawrence Berkeley National Laboratory -- one of the most powerful and versatile sources of electromagnetic radiation in the world -- to reveal some of those secrets.

It was extremely difficult to measure the absorption of light in a single monolayer of graphene, because not much light is absorbed. To do this, researchers had to start with a very bright light. It was spectroscopy to the extreme.

The radiation from ALS, is about 100 million times brighter than that from the most powerful X-ray tube, the source used in a dentist's machine. High brightness means that the radiation is highly concentrated and many photons per second can be directed onto a tiny area of a material.

Scientists use ALS's radiation to look inside materials. "It took some difficult experimental work to make this measurement," said Dimitri Basov, one of the lead researchers. "It was by far the most complicated measurement we have ever done."