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World's First Single-Atom-Thick Fabric
neutron_p writes "Researchers at The University of Manchester have made the world's first single-atom-thick fabric, which reveals the existence of a new class of materials and may lead to computers made from a single molecule. They call it graphene, because it's 'webbed' by extraction of individual planes of carbon atoms from graphite crystal. The nanofabric belongs to the family of fullerene molecules, which were discovered during the last two decades, but is the first two-dimensional fullerene."
Since it is only one type of molecule and only one molecule thick, the refractive index of the material would be constant. So if it had any color at all, it would be a constant color, not a rainbow like oil or a prism produces.
Don't get thrown off by the term "fabric". If you read the article, you'll realize that the applications of this are mainly in integrated circuit fabrication. As far as the health and environmental issues, we're talking about a pure carbon lattice. With this process carbon can act as a semiconductor without dopants such as arsenic, so C-based semiconductors are actually "greener" than current silicon-based chips.
(IANA Chemist but...)
:)
Probably not very. However, as with many thin and light materials, a very good use would be to layer these sheets into thousands of layers. Each sheet layer probably could not be one single molecule; that would be far too brittle, but if someone could figure out a way to neatly link sheets of a regular size (say 10x10 microns), and then stack thousands of them on top of each other, you'd get a very strong (linkage along one plane, and layering interplane), light, and smooth (graphite). You'd end up with flexible and chemically non-reactive materials that happend to be strong as well... Maybe you'd have a very pliable armor, or maybe some sort of non-reactive soft containers (if Nalgene made waterskins)
Or not
0- Eamonman Proud member of DNRC
Actually it's all just hype.
This material was known before.. long before fullerenes even. It's just graphite.
The structure of graphite and the fact that the interplanar bonds are weak has been known for quite a long time.
The news here is that someone actually found a practical way to produce a single graphite layer.
But it's not really a new compound.
The material is made of carbon atoms. I don't think you'll find many people allergic to carbon, since most everyone I've met has been "carbon-based".
However, if this material breaks down into tiny, airborne pieces, it could by-pass the lung's filtering system and lodge itself in the tissue.
Black lung disease is caused by coal dust, and coal is nothing more then carbon and hydrocarbons, both basic biological building blocks for life on earth. Its just that the coal dust gets lodged in the lungs, and the body can't remove it. The irritation then causes problems.
Except glass (usually) has a constant index of refraction (as does bubble film, which you're apparently thinking of). It's the fact that there is chromatic dispersion (simply: different frequencies of light--the colors--travel at different speeds in the medium (giving different refraction angles, and, therefore, different paths and pathlengths). So even though the index of refracton is constant for a _given_frequency_, the fact that the index changes for different frequencies gives the colors (along with multiple reflections from front and back surfaces).
The fact that this stuff is only one molecule thick is much more persuasive. In fact, very thin bubbles are completely transparent to light, because the light cannot refract if the film is less than about a wavelength thick. Since molecules (chains and polymers get a little tricky, of course) are generally much, much smaller than a visible wavelength, this stuff will probably be virtually invisible, unless, as another poster pointed out, it's extremely highly conductive (which would cause a skin-depth effect and probably do more complicated things to light).
Look it up.
People are allergic to either the dander, saliva or urine of cats.
sure sure, off-topic, but correct ;)
It would be really, really weak, because it is so thin. The slightest breeze would destroy it, if you made a macroscopically sized piece. And of course you couldn't see it, or feel it. You wouldn't even know it was there without special instruments.
As bonds go, the inter-atomic bonds in this fabric are strong; but there's only one layer! Compared to like ten million atomic layers in a typical fabric. The carbon bonds aren't *that* much stronger that you can make a ten million times thinner (and weaker) piece and still have it be strong.
It's the same with nanotubes; they're as strong as tubes get, considering that they're only a nanometer in diameter. But compared to the weakest macroscopic thread you could imagine, an individual nanotube is far weaker. Proposed nanotube cables would use trillions of them in parallel to carry a load.
Yes, refraction is due to a change in group speed between media: if in one medium, the constituents interact a lot more with the light than the constituents of the other medium, the group speed in the highly interacting medium tends to be slower than in the other. Because of the requirement that various boundary conditions at the mediums' interface must be matched, the wavefronts tend to bend at the interface, and one has refraction.
You're right, in that absorption of all colors but, say, blue by some object will make that object look blue. BUT one may also separate colors into different portions of an object -- the light of different colors has simply ended up in different spots, but hasn't been permanently absorbed or attenuated (as in interference colors in bubbles, or oil slicks, etc.). One way to obtain this is to simply reflect light multiple times off of two parallel (or nearly parallel) surfaces, as in a bubble or a pane of glass. Very little of the light is really absorbed, just shuttled from place to place.
I think that we're probably just thinking of different "complementary" pictures of light -- you're focusing (agh!) on the photon, discrete picture, and I'm focusing on the continuum, wavelike picture. I'm essentially trying to scale down what I know about wave mechanics to spatial regimes where those wave mechanics get pretty strange (due to the wavelength vs. molecular size discrepancy). I think you're applying some scattering theory (or at least some good intuition) to the problem. Of course, if we're both careful, we should end up with exactly the same answer.
So isn't this subject to the same inherent photon-manipulating characteristics as other carbon atoms?
Oh, absolutely. However, one must recognize that things can scatter light in very strange ways depending on their spatial relationships to each other. Carbon atoms in graphite and diamond are identical, but their locations relative to each other make all the difference between opaque grey, and transparent brilliance. Same with water vapor in the air (humidity in the air doesn't scatter light by itself, but get those water molecules clustered together in big enough drops -- say, in a cloud -- and they scatter light quite effectively).
Basically, what I'm getting at is that you have to have some semblance of order on a scale comparable to the wavelength of light you want to interact with, to ever scatter that light. Because this "cloth" is so thin, I doubt it'll interact with the light much at all, unless you have wavefronts incident on it at grazing angles -- then you have the chance of the light interacting with it over larger spatial domains, and getting some scattering.
I dunno. Time to look at boobies. They scatter quite well. Especially when they hear geek-talk.
I agree with your point that this material certainly shouldn't be treated like it has a bulk index of refraction--a monatomic layer is definitely in the realm of weird quantum effects.
It should be noted that this system can't be treated like distinct atoms, however. It's effectively one giant molecule, with a very complicated electron cloud surrounding a layer of nuclei. In the ideal case where this system is perfectly flat, you (er, a solid state physics grad student) can probably come up with a reasonable idea of what its absorption and emission spectra look like. (I wouldn't be surprised if a creature like this showed not insignificant fluorescence.) On the other hand, as soon as you start to bend this stuff, or introduce small defects, or do anything else to it, it gets a lot more complicated. You get a whole pile of nonlinear effects, and I wouldn't be surprised of there were broadband absorption. (Actually, that absorption could be used to tell you all about the stresses and defects in a particular sample of the material. Can I have my patent now?)
~Idarubicin
That's so...stone age. Seriously :-) Obsidian can be fasioned into blades with an edge that's only 1 atom thick (I've seen pictures of an electron micrograph in a book, I wish I could find some online to post). Obsidian in fact is used in some cases as surgeon's scalpels because it can be made so much sharper than steel.
>1) Why is there a relationship between >conductivity and index of refraction?
There is a relationship between dielectric constant (not exacty conductivity) and refractive index. The dielectric constant involves the ability of a material to attenuate an electric field, through the dipole moment and polarizability of the material. Light (or more exactly, electromagnetic radiation) is just alternating electric and magnetic fields.
>2) Index of refraction is the ratio of the speed of light in vacuum to the speed of light in the material. As a result, you always have a number greater than 1. What does a negative I-of-R mean physically? The speed of light in the material would have to be negative? Would it reflect the beam rather than refract it?
If you shine light into a pool of water at a 45 degree angle to the vertical, the beam bends at a >45 degree angle. If the same pool of water had a negative refractive index, the beam would bend at a 45 degree angle.
One interesting thing about the material described is that graphite is about 1000X as conductive parallel to the sheets as perpendicular to them. Light with its electric field in the plane of the sheet would see an almost metallic surface, while light polarized perpendicular to it would just see a layer of carbon atoms. It might make a really efficient thin film polarizer.
Reflection of radio waves has to do with electrons in the material that move because of the electrical field of the radio waves. Conductivity obviously has to do with how well electrons can move. You can regard light to some extent as an high-frequency version of radio waves, if you ignore the quantum effects that become important at those frequencies.
2) Index of refraction is the ratio of the speed of light in vacuum to the speed of light in the material. [...] What does a negative I-of-R mean physically?
I think the parent poster was incorrect. The index of refraction is complex, i.e., has an imaginary component. That is a mathematical trick; if you describe a wave as
then the imaginary component in n will cause the wave to dampen out while propagating.A refractive index can actually be smaller than 1, which means that light propagates faster than the speed of light (can happen with X rays). This does not violate Einstein's laws, since what counts is how fast you can transmit information and you can't transmit information with a constant wave.
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