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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