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2.

As I wrote here , physics Nobel Prize this year was awarded to Geim and Novoselov by the discovery of graphene. What makes graphene so special that it deserves this distinction?

Graphene is a crystalline form of carbon and one of the few materials that is two dimensional. That means it is very thin and which consists of only one plane of atoms. Like a sheet of paper, extends far into space in two dimensions than in the third dimension. The existence of a two-dimensional material by itself and was received with surprise news in the scientific world when it created the graphene for the first time in 2004. This is due to the fact that it had been shown theoretically that there should be a two-dimensional material. Due to fluctuations in its crystalline structure, resulting in the breaking of the 2D structure, any such fine material should be changed. But to the surprise of everyone if the graphene was stable when its synthesis was achieved. And so it is a very interesting material, although at first the interest was rather academic.

watermark Despite its appearance - the graphene is so thin that it hardly absorbs light and almost transparent - it is very robust. It is very difficult to break and is 200 times stronger than steel.

Another feature of graphene is that it is a good electronic conductor. This is because the organization of electrons in chemical bonds that form the carbon atoms in the plane. Carbon has four electrons that can participate in the formation of these links, but a carbon atom in graphene has only three neighbors. The three links to a carbon atom and its neighbors are called σ bonds (sigma) and are very stable. But since there are only three neighbors, only three electrons in each atom are attached to a link σ. The fourth electron forms a link called π (pi), but not sure which of the three neighbors. The electron is neither located nor attached to any atom. It is these electrons in π bonds responsible for the electronic conductivity of graphene. Like free electrons in a metal move without difficulty and represent the charge carriers in electronic conduction, the π electrons in graphene move easily, thus contributing to driving. Moreover, this complex behavior of electrons in σ and π bonds are responsible flat nature of graphene and its honeycomb appearance.

Graphene also has a wide variety of exceptional features such as high thermal conductivity and a host of interesting quantum effects. Does

graphene practical applications? Maybe in microelectronics and microprocessors such as transistors or integrated circuits, but for this to find everyday life path has yet to spend enough time. Alternatively graphene powder mix with a plastic socket. With a small amount of plastic insulating graphene can be transformed into a driver. And thanks to its transparency can be used as transparent electrode. We'll probably see many applications of graphene, and it therefore deserves the Nobel Prize.

For me the most curious is how it succeeds in producing graphene. Chemical method is not very developed, or need large and expensive instruments. In 2004, Geim and Novoselov used tape to peel layers of a graphite crystal. Paste these films on a silicon oxide surface is eventually in a sheet of graphene on silicon. Easy, right?

For those seeking more detailed information on graphene, there are two texts by Andre Geim and Novoselov Konstantin (free access): The Rise of
Graphs: http://arxiv.org/abs/cond- mat/0702595
Graphene: Status and Prospects : http://arxiv.org/abs/0906.3799

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graphene physics Nobel Prize for

announced today that the Nobel Prize in Physics 2010 was awarded to Andre Geim and Novoselov Konstantin University of Manchester for the manufacture of graphene. In the 90 the two managed to peel graphite, the material used as a quarry in pencils, sliced \u200b\u200bso thin that eventually reduced to a single layer of atoms, graphene. Both, graphite and graphene, are pure forms of carbon and only this element is necessary for their synthesis. It is the finest material ever produced and has physical and chemical characteristics very special. For example, although not a metal, is a good electronic conductor. It is also clear because of its small thickness. It really is a unique material that will have a huge impact on technological development.

graphene model, every gray ball represents a carbon atom. Each atom is connected by a chemical bond with three atoms neighborhood, and they form a hexagonal network.

is the second Nobel Prize to be awarded for results related to the pure carbon. In 1996, the Nobel Prize for chemistry was awarded to Robert Curl, Harold Kroto and Richard Smalley for the discovery of the molecule C 60 . It is known as the Buckminsterfulereno and consists of a molecule shaped like a soccer ball made up of 60 carbon atoms.
Since there is currently much interest in investigating this type of carbon-based materials, I will write some articles about it here. In four parts, try to explain each of the states in which carbon can be found:

0. Buckminsterfulereno
1.
carbon nanotubes 2. Graphene
3. graphite and diamond

I'm still not entirely sure what order I'm going to write but just start from the No. 2 because it is the most current. So if interested, I invite you to return regularly to read new articles.

Here is a picture that represents the relationship between the buckminsterfulerenos graphene, carbon nanotubes and graphite. Graphene pieces can be curved to mold fullerenes, roll up to create nanotubes or stacked to form graphite. The image is in the publication The Rise of Graphene to Geim and Novoselov , which is freely accessible here.

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graphene is the first planet in the habitable zone


Liquid water is a prerequisite essential for life as we know. Almost any kind of life is based to some extent in the presence of this molecule that consists of an oxygen atom and two hydrogen atoms. 50% of the mass of the human body is due to water. To keep liquid on a planet, it requires a proper air pressure and an average temperature suitable. Circling the star Gliese 581 has found a planet that may have just the right values \u200b\u200bof pressure and temperature to hold liquid water, and thus one of the modules necessary for life. The planet named planet G is in the habitable zone, which means, at a distance from the star where temperatures are neither very high nor very low. It also has a mass similar to Earth, allowing an atmosphere similar to ours. These two factors together mean that liquid water can exist on its surface.

Steven Vogt of the University of California Santa Cruz and colleagues describe here the reanalysis of their data. Over 11 years accumulated spectrum of the star Gliese 581, and comparing these with data acquired by other techniques, conclude that there are two additional planets to the four already known. The interesting thing is that for the first time there is a planet right in the middle of the habitable zone. I've written before about the search for exoplanets with the Kepler space telescope, planets that circulate to other stars and not the sun Although Kepler is becoming more exoplanets, these new results were acquired with telescopes stationed on Earth, especially with the WM Keck Observatory Hawaii. Is measured with a spectrometer emititda radiation by the star. Small changes in wavelength of this radiation indicate the presence of planets. The magnitude of the change in wavelength depends on the mass of the planet and its distance from the star.

Image: Comparison of the orbits of Mercury, Venus and Earth in the solar system Gliese 581. The Gliese 581 system is much smaller than our solar system. (Image from Steven Vogt, http://www.ucolick.org/ ~ vogt /)

Planet G has at least three times the mass of Earth. It's enough to trap gas in its surface and create an atmosphere. The moon, by comparison, has no atmosphere because of their small mass, one sixth that of Earth. A year on the planet G has only 37 days and the distance to the sun is about one sixth of the Sun to Earth. In our solar system would mean very high temperatures on its surface. But Gliese 581 is a red dwarf, dimmer and cooler than the Sun to planet temperatures may be similar G to ours. It is also curious that there is no day. As always see the same side of the Moon from Earth, the planet G always shows the same side towards Gliese 581. So on one side is always the other day while in perpetual darkness rules.

course, the results do not confirm the presence of liquid water on the planet. All you can say is that there is some likelihood of its surface. And with the water, extraterrestrial life becomes a real possibility. Steven S.

Vogt, R. Paul Butler, Eugene J. Rivera, Nader Haghighipour, Gregory W. Henry, & Michael H. Williamson (2010). The Lick-Carnegie Exoplanet Survey: A 3.1 M_Earth Planet in the Habitable Zone of the Nearby Star Gliese 581 M3V arXiv arXiv: 1009.5733v1