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Graphene is a one-atom-thick planar sheet of sp2-bonded
carbon atoms. The arrangement forms a densely packed honeycomb
that can be visualized as an atomic-scale chicken wire made of
carbon atoms and their bonds. The
carbon-carbon bond length in graphene is about 1.42 Ĺ (angstroms)
which compares to a bond length of 1.50 Ĺ for C-C single bond
as found in the ethane
molecule. (Note: The angstrom (Ĺ) is an internationally recognized
unit of length equal to 0.1 nanometre or 1 × 10 -10
meters.
Graphene
is the basic structural element of some carbon allotropes including
graphite,
carbon
nanotubes, and fullerenes.
The Nobel Prize in Physics for 2010 was awarded to Andre Geim
and Konstantin Novoselov "for groundbreaking experiments regarding
the two-dimensional material graphene".
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Graphene
structure shown using the Jmol Applet--The Graphene Molecule
shown above was created using ArgusLab
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Rotate the Graphene molecule
(Hold
the left mouse button down over the image and move the mouse
to rotate the graphene molecule -- you can easily see that
graphene is only ONE molecule thick).
Notice
that each carbon atom is the same distance to each of its
neighboring carbon atom.
What
is the bond length for a Carbon-Carbon bond in Graphene?
Click
right mouse button-->Render-->Scheme--> Ball and
Stick
Double
click left mouse bottom on any carbon atom, then drag +
to nearby carbon atom and double click again to get distance.
View
other 3-D allotropes of Carbon:
Graphite
molecule
Diamond
molecule
Fullerene
Carbon
Nanotube
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Potential
applications
New
Materials
As
of 2009, graphene appears to be one of the strongest materials
ever tested. Measurements have shown that graphene has a breaking
strength 200 times greater than steel.[1]
Graphene
transistors
In
2008 Dr Kostya Novoselov and Professor Andre Geim from The School
of Physics and Astronomy at The University of Manchester reported
in the journal Science that graphene can be carved into tiny electronic
circuits with individual transistors having a size not much larger
than that of a molecule. [2]
Single
molecule gas detection --Graphene makes an excellent sensor
due to its 2D structure. The fact that its entire volume is exposed
to its surrounding makes it very efficient to detect adsorbed
molecules. Researchers at the University of Manchester --Centre
for Mesoscience and Nanotechnology-- have used the world's thinnest
material to create sensors that can detect just a single molecule
of a toxic gas. [3] The operational principle of such sensors
is based on changes in electrical conductance of a number of base
materials when gas molecules are adsorbed on their surface. The
existing sensors can detect gases in concentrations as small as
1 part per million or less.
Integrated
circuits --The unique properties of thin layers of graphite
make the material attractive for a wide range of potential electronic
devices. Researchers have experimentally demonstrated the potential
to replace copper for interconnects in future generations of integrated
circuits. Because graphene can be patterned using conventional
microelectronics processes, the transition from copper could be
made without integrating a new manufacturing technique into circuit
fabrication.
Graphene
biodevices -Graphene's modifiable chemistry, large surface
area, atomic thickness and molecularly-gatable structure make
them excellent candidates for mammalian and microbial detection
and diagnosis devices [5]
One
of the most ambitious biological application of graphene is for
rapid, inexpensive DNA sequencing. [6]
References
and Readings
1 Lee, C.
et al. (2008). "Measurement of the Elastic Properties and Intrinsic
Strength of Monolayer Graphene". Science 321 (5887): 385. doi:10.1126/science.1157996.Abstract:
http://www.sciencemag.org/cgi/content/abstract/321/5887/385.
2 L. A. Ponomarenko,
F. Schedin,1 M. I. Katsnelson, R. Yang, E. W. Hill, K. S. Novoselov,A.
K. Geim "Chaotic Dirac Billiard in Graphene Quantum Dots"
Science 18 April 2008: Vol. 320. no. 5874, pp. 356 - 358. Abstract:
http://www.sciencemag.org/cgi/content/abstract/320/5874/356
3 Schedin,
F. et al. (2007). "Detection of individual gas molecules adsorbed
on graphene". Nature Mater 6 (9): 652–655. Abstract: http://www.nature.com/nmat/journal/v6/n9/full/nmat1967.html
4 Murali,
R. Brenner, K. Yang, Y. Beck, T. Meindl, J. D. Resistivity of
Graphene Nanoribbon Interconnects. Electron Device Letters, IEEE,
June 2009 Volume: 30, Issue: 6: 611-613 Abstract: http://ieeexplore.ieee.org/xpl/freeabs_all.jsp?arnumber=4968006
5 Mohanty,
Nihar; Vikas Berry (2008). "Graphene-based Single-Bacterium Resolution
Biodevice and DNA-Transistor— Interfacing Graphene-Derivatives
with Nano and Micro Scale Biocomponents". Nano Letters 8: 4469–76.
Abstract: http://pubs.acs.org/doi/abs/10.1021/nl802412n
6 Xu, M. S.
Xu; D. Fujita and N. Hanagata (2009). "Perspectives and Challenges
of Emerging Single-Molecule DNA Sequencing Technologies". Small
5 (23): 2638–49. Abstract: http://www.ncbi.nlm.nih.gov/pubmed/19904762
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