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May 28, 2009

Carbon Atomic Chains from Graphene


Optimized geometries of carbon atomic chains constrained by two GNRs with various types of edges. (a) a 8-sp-atom chain bridging two GNRs with 5-7 edges,
(b) a 9-sp-atom chain bridging two GNRs with zigzag edges, (c) a 10-sp-atom chain bridging two GNRs with armchair edges, (d) a 12-sp-atom chain bridging two GNRs with armchair edges. The unit for bond length is Å.


Physics Letters has an article on carbon atomic chains being produced from graphene.

Stable and rigid carbon atomic chains were experimentally realized by removing carbon atoms row by row from graphene through the controlled energetic electron irradiation inside a transmission electron microscope. The observed structural dynamics of carbon atomic chains such as formation, migration, and breakage were well explained by density-functional theory calculations. The method we reported here is promising to investigate all-carbon-based devices with the carbon atomic chains as the conducting channel, which can be regarded as the ultimate basic component of molecular devices


4 pages of supplemental material.







Nanowerk has coverage

"Our approach to realize freestanding carbon atomic chains employs energetic electron irradiation inside a transmission electron microscope," Kazu Suenaga explains to Nanowerk. "A graphene nanoribbon was continuously thinned from its two open ends by removing carbon atomic rows. This thinning process stops when the number of carbon atomic rows becomes two or one. This way we could reproducibly fabricate single and double freestanding carbon atoms chains."

Suenaga, who heads the Nanoscale Characterization Team at the AIST Carbon Center in Japan, points out that these chains show a remarkably good stability with a length up to a few nanometers even under the irradiation of energetic 120 keV electron beams.

Although the potential applications of a carbon atomic chain are still unclear, such an ideal one-dimensional carbon chain can be regarded as an ultimate basic component for electronic devices.

Suenaga mentions that the chains definitely show a quantum transport and one can therefore anticipate to integrate a million of the carbon chain devices just by patterning a single graphene layer. "This can be a real merit as opposed to the case of nanotubes, because the integration of nanotube devices on a substrate has turned out to be quite difficult," he says.

The researchers expect excellent electronic transport properties for cumulenes (.C=C=C=C.) and we can therefore assume that carbon atomic chains can serve as outstanding sensors, since the electronic transport properties should be significantly affected by dopants and absorbent (such as some chemical or biological species).

Carbon atomic chains may also find possible applications in logical devices, such as switches or bi-stable memory. According to Suenaga, the change of contact of such carbon chains with graphene has recently been proposed as a mechanism for the atomic-scale switches


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