from Wiktionary, Creative Commons Attribution/Share-Alike License
- n. A polycyclic aromatic hydrocarbon consisting of five fused benzene rings; an isomer of pentacene.
from the GNU version of the Collaborative International Dictionary of English
- n. A hydrocarbon (C�H�) extracted from the pitchy residue of coal tar and petroleum as a bluish fluorescent crystalline substance.
from The Century Dictionary and Cyclopedia
- n. A crystalline unsaturated polycyclic hydrocarbon, , with blue fluorescence, which is found in the pitch-like residues from the distillation of lignite-tar and petroleum. It is also made synthetically.
Sorry, no etymologies found.
Like the carbon-60 crystals, superconductivity in picene is believed to be related to p-electrons.
In particular, they don't know whether the potassium atoms lie within the picene planes or between the planes - although they believe the former to be more likely.
But according to Prassides, the superconductivity comes as a surprise because picene molecules arrange themselves in 2D planes much like graphite.
Now, Ryoji Mitsuhashi and colleagues at Okayama University in Japan have found that crystals made from the hydrocarbon picene and potassium atoms are superconductors at temperatures up to 18K.
The team begin with an ultrapure picene crystal that is then heated in the presence of potassium for several days.
Only one sample - containing 3.1 rubidium atoms per picene molecule - was superconducting with a Tc of about 7K.
The team studied crystals with a range of potassium concentrations from one potassium atom per picene molecule to 5.1 per molecule.
It turns out, however, that by pure coincidence, picene has two p-electron states with the same energy.
(PhysOrg. com) -- Scientists from Okayama University in Japan have discovered that the hydrocarbon picene can be made to superconduct when potassium atoms are interspersed with the picene crystals and the doped picene is cooled.
Professor Kubozono said picene is the first example of a hydrocarbon superconductor, although scientists have been able to create superconductors of the carbon compound fullerene (C60) doped with potassium.