Carbon  

In General > s.a. molecular physics.
* Forms: Carbon occurs naturally as the soft, black graphite and as diamond; The only difference between the two is the arrangement of the atoms; The same carbon atoms can also be arranged into a 1-atom thick chicken-wire pattern called graphene, and rolled up into minuscule nanotubes only 10 atoms across with very special properties.
* Formation: It forms at the interior of burning stars in what is called the triple-α process, by which two α particles react to form 8Be, which in turn reacts with a third α particle to form an excited state of 12C called the Hoyle state.
* Diamond: Created at high p and T inside Uranus, conditions recreated in the lab [@ news pn(99)oct].
* Radiocarbon dating: Began in 1949 with Willard Libby's suggestion that the amount of 14C left in a fossil object could provide an estimate of how old the object was; The thinking was that the organism, while it was alive, would constantly ingest enough of the rare 14C to replace those nuclei that were decaying into 14N (the other products being an electron and a neutrino); But as soon as the organism died, the ratio of 14C/12C would begin to drop exponentially since the 14C was no longer being replaced. Measuring the ratio in terms of radioactive half-lives would provide a good estimate of the fossil.
@ Radiocarbon dating: Beck et al Sci(01)jun; Holt et al PRL(08) + pn(08)jan, Maris et al PRL(11) + news(11)may [explanation of long 14C half-life].
@ Other topics: Agranat et al JETPL(97) + pn(98)feb [liquid]; Jin et al PRL(09) + van Ruitenbeek Phy(09) [atomic wires]; Fano AJP(10)apr [atmosphere-ocean carbon cycle]; news PRfocus(10) + ns(10)nov [ultra-hard graphite]; Hjorth-Jensen Phy(11)may [formation in stars]; news nbf(11)oct [new superhard form of glassy carbon]; Gomes et al Nat(12)mar + news pw(12)mar, at(12)mar [artificial, "molecular" graphene with arrays of CO molecules].

Graphene
* Idea: A 2D honeycomb lattice of carbon discovered in 2004, which has a wealth of special mechanical and electronic properties; Many of the latter arise from the fact that graphene is a semiconductor with zero energy gap between its valence and conduction bands; Near where the two bands meet, the relationship between the energy and momentum of the electron is described by the Dirac equation and resembles that of a photon; These bands, called Dirac cones, enable electrons to travel through graphene at extremely high speeds; > s.a. sound [acoustic analog].
* Nanotubes: Discovered in 1991 by Iijima, they consist of sheets of graphene rolled-up into cylinders of 1–10 nm diameter, so they are quasi-1D; Extremely stiff, with a Young's modulus of 1.0–1.8 TPa (100 times the tensile strength of steel), they buckle elastically; They can be better conductors than copper or semi-conductors, depending on how they are rolled up, and are excellent heat conductors; > s.a. technology.
@ General references: Juričić et al PRB(09)-a0905 [metal-insulator critical point]; Novoselov pw(09)aug [and graphane]; Guinea Phy(10) [properties of bilayers]; news pt(10)oct [Nobel Prize]; Thongrattanasiri et al PRL(12)-a1106 + news pw(12)jan, Phy(12) [total light absorption]; Nair et al Sci(12)nat + news(12)jan [permeation properties of graphene membranes]; news Phy(12), sp(12)mar [graphyne]; news ns(12)nov [semiconducting graphene]; Katsnelson 12; > s.a. electricity; rotation.
@ Electron dynamics: Kotov et al RMP(12) [electron-electron interactions]; Quimbay & Strange a1311 [2D Dirac oscillator model]; Volovik & Zubkov AP(15)-a1412 [emergent geometry experienced by fermions in the presence of dislocations]; > s.a. electron.
@ Applications: news pw(06)nov [and spintronics]; news pw(11)mar [electronic properties and relative layer rotation]; Jenkins AS(12)#5 [in high-frequency electronics]; news pw(13)mar [loudspeakers]; Ribeiro & Scheel PRA(13)-a1310 [as a shield for vacuum fluctuations]; news pw(13)nov [room-temperature ferromagnetism]; Glazov & Ganichev PRP(14) [optical and optoelectronic properties]; Foa Torres et al 14 [nanomaterials]; news pw(15)jul [battery performance].
@ Nanotubes: Dresselhaus et al pw(98)jan; Dekker PT(99)may; Chen et al Sci(99)jul; issue pw(00)jun; Avouris PT(09)jan [electronics and photonics].
@ Variations: Abreu et al JHEP(11)-a1002 [supersymmetric model]; Bakke et al AP(12) [topological defects, Kaluza-Klein approach]; Zhang et al PNAS(15) [penta-graphene, properties including negative Poisson ratio]; Mullen et al PRL(15)-a1408 + news PhysOrg(15)jul [3D "hyper-honeycomb"]; news nat(15)jun [new materials].
@ And field theory: Pachos CP(09) [and anyons]; Fialkovsky & Vassilevich IJMPA(12)-a1111-conf [quantum field theory methods]; Iorio & Lambiase PLB(12) [Hawking–Unruh phenomenon]; Iorio JPCS(13)-a1304; Bastos et al IJMPA(13) [non-commutative graphene]; Iorio IJMPD(15)-a1412 [curved graphene, rev]; de Paula et al FBS(15)-a1511 [optical conductivity computation]; > s.a. electroweak theory [Higgs boson]; quantum field theory.
@ Related topics: news Cornell(13)jul [as a semiconductor]; Dobson et al PRX(14) [many-body quantum effects, cohesive force between micron-sized graphene flakes]; San-Jose et al PRX(15) [Majorana particles]; > s.a. topology in physics; types of coherent states.
> Field theory and gravity-related topics: see emergent gravity; gauge theories.


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