Thursday, July 24, 2008

Heavy Connections

Water, water everywhere. We know what it is, right? depends.

For example, water cannot be compressed, it's less dense when frozen and it exists in three states (gas/liquid/solid) within a very moderate temperature range and, according to researchers, quantum effects are the reasons why.

"Water is a remarkable liquid — for example it has unusually high surface tension and it becomes less dense when it freezes. Quantum physics, through its effects on the hydrogen bonds, could be playing a significant role in water’s weirdness, Soper says. “Probably all the properties of water are affected by the hydrogen-bond length.”

Another substance with magical properties is graphene, an unrolled nanotube that exhibits characteristics equally as bizarre and wonderful as H20.

“Our research establishes graphene as the strongest material ever measured, some 200 times stronger than structural steel,” Hone said. “It would take an elephant, balanced on a pencil, to break through a sheet of graphene the thickness of Saran Wrap.”

When varying amounts of electric current is applied to graphene via an STM (Scanning Tunneling Microscope), unusual properties emerge.

"The carbon atoms in graphene are arranged at the corners of hexagons, as in chicken wire, with three of each atom's four electrons involved in molecular bonds with its neighbors; these are sigma orbitals that lie in the plane of the material. The remaining electrons are in pi orbitals extending above and below the plane. The hybridization of the pi orbitals spreads across the graphene sheet, and the unconfined electrons are free to move as high-speed "relativistic quasiparticles," so-called Dirac fermions which act as if they have no mass."

Last but not least, click here to learn why graphene has become the Wonder Boy of Quantum and Condensed Matter physics.
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