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New Form of "Mobius" Carbon Predicted
KentuckyFC writes "We've seen carbon nanotubes, buckyballs, and chickenwire. Now materials scientists have created a computer model of a Mobius strip fashioned from strips of graphene — a molecule that would have a single surface and only one edge. (Other groups have made Mobius-like organic molecules but never out of carbon sheets.) The model allows the researchers to determine the physical and chemical properties of the molecules and how these depend on the number of twists in the strip. The team says, for example, that 'Mobius carbon' should be stable to temperatures of at least 500 Kelvin (abstract). But the most exciting prediction is that strips with an odd number of half twists should have a dipole moment that would cause them to self-organize into a crystal. That implies that there's a new type of carbon made entirely of Mobius strips ready to be made by any chemists with a good supply of graphene (maybe these guys)."
That's not entirely true...
http://en.wikipedia.org/wiki/Carbon_nanotube#Synthesis
Well, it will still be made up of graphene when it comes to looking at atomic energy levels. Band gap is the primary source of light interactions, and as it will still be close to zero band gap (unless the asymmetry thrown into long range hybridization screws it up in ways I am not thinking of), and should be absorbing most photons.
So, it'll probably look the same as graphite, but would probably diffract photons with wavelenghts like 10nm due to it having a longer-range crystal structure than normal crystals (which only diffract in the X-rays). The crystals might do things like diffract in the high energy UV, assuming the UV doesn't all get absorbed by the graphite.
Graphene is a (basically) 2-D sheet that can be fairly large. Imagine the sheet the size of a blanket. Now make a mobius strip out of it.
The fact that it's "one sided" should only really come into play in that long range hybridization of the pi orbitals will interfere with each other -- presumably causing the weird effects their model predicts.
Doubt it. Things can still react on both sides of the locally 2-sided graphene sheet.
Graphene has some pretty interesting electronic properties. Its bandgap (the essential component of all semiconductors)
Graphene is a semimetal. The bandgap is zero in suspended graphene. Epitaxial graphene on SiC has a small gap (0.1meV) but below Fermi level, so not very useful.
can be manipulated by changing the length of the sheet; as the sheet becomes infinitely long, the bandgap approaches zero.
Not correct. The bandgap of a narrow ribbon depends on the width (not the length) of the ribbon. Above 10nm there is no gap, below there is, regardless how long it is.
As a result, it could hold potential in photovoltaics for light capture or LEDs for light emission where capture/emission is tunable based on the size of the particle (which is pretty easy to manipulate).
Well, this is totally unrelated as electron-hole pair recombination requires a junction.
Another article popped up on Slashdot recently suggesting graphene could be used for super high-capacity memory storage: http://hardware.slashdot.org/article.pl?sid=08%2F12%2F18%2F2332251.
From the paper they mention that active electrons have near-zero effective mass. Since electron mobility is inversely proportional to effective mass, resistivity approaches zero (in essence, we approach superconductivity).
No. mobility is finite, because you need to take into account of the so called saturation velocity. Besides, near-zero doesn't mean zero, so conceptually the two are completely different.
"[nanotubes]...currently impossible to make more than a trace amount of."
Only for large values of "trace amounts" such as this proposed 400 ton/yr plant that when completed will compete with existing plants.
Also it maybe obvious to some but I'm having difficulty is understanding how this discovery would help in production of said nanotubes?
And did you exchange a walk on part in the war for a lead role in a cage? - Pink Floyd.
But... you can put about a pint into a Klein Stein.
RUGBYRUGBYRUGBY
Locally (to the individual atoms, for example) a Mobius molecule is double-sided. Each carbon atom is fixed in a plane in graphene, though the point here is that the plane is interestingly warped. A chlorine atom could attack a carbon atom from above the plane and a bromine atom could attack from below the plane, and that would be a physically meaningful description. "Above" and "below" are of course arbitrary distinctions; let's use "a" and "b" in this post. From the perspective of Carbon #1 of the 150 carbon atoms in this molecule, the situation is nothing special; there's a bit more bond strain from the way the lattice is twisted, but it still generally behaves like a carbon atom.
What makes a Mobius molecule interesting is when you something else along its surface. For example, kinesin is a protein that works like a set of molecular legs. Picture a regular, non-Mobius single-walled carbon nanotube, a rolled-up sheet of graphene. This tube has an exterior surface (the "a" position)and an interior surface ("b")- it is two sided. To get a kinesin molecule from the exterior surface to the interior surface or vice versa, you must either cut through the graphene lattice or walk to an edge of the cylinder and flip around. There is not a smooth, continuous path from position Carbon #1-a to #1-b for a regular nanotube.
However, for a Mobius nanostrip, that added half-twist makes the "exterior surface" continuous with the "interior surface," making a smooth path possible. If you place kinesin at Carbon #1-a and have it walk around the strip, halfway through the course (for a strip with one half-twist), the kinesin will be at Carbon #1-b (in other words, back at Carbon #1, but in a local sense, on the other side of the sheet), and its orientation will be flipped 180 degrees from the original. If the kinesin keeps going, eventually it returns to its original orientation at Carbon #1-a. If you put a kinesin molecule at both 1-a and 1-b and sent them off walking in opposite directions, they would eventually collide.
Locally, 1-a is on the opposite side of 1-b, but a kinesin molecule can smoothly and continuously walk from 1-a to 1-b (or any other point) without breaking bonds in the graphene lattice or flipping around an edge to another side. Therefore, in terms of its entire shape, a Mobius molecule is one-sided.
"FDA staff reviewers expressed concern about the number of patients who were left out of the study because they died."
Water boils at 373K. If you call 127K a "handful of degrees" you are either an american or a retard with really big hands. 500 Kelvin = 226.85 Celsius (water boils at 100c)
If I have to explain it it's not funny!