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 \(^{14}\)C 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 \(^{14}\)C to replace those nuclei that were decaying into \(^{14}\)N (the other products being an electron and a neutrino); But as soon as the organism died, the ratio of \(^{14}\)C/\(\,^{12}\)C would begin to drop exponentially since the \(^{14}\)C was no longer being replaced. Measuring the ratio in terms of radioactive half-lives would provide a good estimate of the fossil.
@ General references: Hazen 19.
@ 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]; 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.
@ Bilayers: Guinea Phy(10) [properties]; MacDonald Phy(19) [overview].
@ 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]; news sn(19)aug [microprocessor with transistors made with carbon nanotubes].
@ 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. chaotic systems; topology in physics; types of coherent states; types of superconductors.
> Field theory and gravity-related topics: see emergent gravity; gauge theories.

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