From Berkeley Labs: “Electronic Life on the Edge”

Berkeley Lab scientists discover the edge states of graphene nanoribbons

By Paul Preuss
May 08, 2011

“As far back as the 1990s, long before anyone had actually isolated graphene – a honeycomb lattice of carbon just one atom thick – theorists were predicting extraordinary properties at the edges of graphene nanoribbons. Now physicists at the U.S. Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab), and their colleagues at the University of California at Berkeley, Stanford University, and other institutions, have made the first precise measurements of the edge states of well-ordered nanoribbons.

A graphene nanoribbon is a strip of graphene that may be only a few nanometers wide (a nanometer is a billionth of a meter). Theorists have envisioned that nanoribbons, depending on their width and the angle at which they are cut, would have unique electronic, magnetic, and optical features, including band gaps like those in semiconductors, which sheet graphene doesn’t have.

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Graphene nanoribbons are narrow sheets of carbon atoms only one layer thick. Their width, and the angles at which the edges are cut, produce a variety of electronic states, which have been studied with precision for the first time using scanning tunneling microscopy and scanning tunneling spectroscopy.

‘ Until now no one has been able to test theoretical predictions regarding nanoribbon edge-states, because no one could figure out how to see the atomic-scale structure at the edge of a well-ordered graphene nanoribbon and how, at the same time, to measure its electronic properties within nanometers of the edge,’ says Michael Crommie of Berkeley Lab’s Materials Sciences Division (MSD) and UC Berkeley’s Physics Division, who led the research. ‘ We were able to achieve this by studying specially made nanoribbons with a scanning tunneling microscope.’ ”

See the full article here.