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Diphosphine
Diphosphine, also called diphosphane, biphosphine, or hydrogen hemiphosphide, is the liquid phosphorus hydride P₂H₄, the phosphorus analog of hydrazine, best known as the impurity that makes commercial phosphine ignite spontaneously in air.
Dipicolinic acid
Dipicolinic acid (pyridine-2,6-dicarboxylic acid, DPA) is a pyridinedicarboxylic acid that accumulates as a calcium chelate in Bacillus and Clostridium endospores, conferring heat resistance, and serves as a tridentate ligand in coordination chemistry.
Dipolar Bose–Einstein condensate
A dipolar Bose–Einstein condensate is a Bose–Einstein condensate in which long-range, anisotropic dipole–dipole interactions dominate, producing quantum droplets and supersolids; the first was made with chromium atoms in 2005.
Dipolar Bose–Einstein condensate of dysprosium
A dipolar Bose–Einstein condensate of dysprosium is an ultracold gas of dysprosium atoms sharing one quantum wavefunction, first created in 2011, in which magnetic interactions between atoms dominate.
Dipolar quantum droplets
Dipolar quantum droplets are self-bound, liquid-like clusters of ultracold atoms in which quantum fluctuations arrest collapse, first observed in magnetic dysprosium atoms at Stuttgart in 2016.
Dipolar quantum gas
A dipolar quantum gas is an ultracold atomic gas, typically a Bose–Einstein condensate, whose atoms interact through long-range magnetic dipole forces, producing quantum droplets and supersolids.
Dipolar quantum gas of dysprosium
A dipolar quantum gas of dysprosium is an ultracold gas of dysprosium, the most magnetic element, first Bose-condensed in 2011 and since used to create quantum droplets, supersolids, and vortices.
Dipolar supersolid
A dipolar supersolid is a state of ultracold quantum matter, proposed by Eugene Gross around 1960, in which superfluid flow coexists with a crystal-like density modulation, first observed in 2019.
Dipolar-octupolar pyrochlore
A dipolar-octupolar pyrochlore is a cubic magnetic pyrochlore oxide, of formula R2M2O7, whose rare-earth ions carry a Kramers doublet with two dipolar and one octupolar pseudospin component.
Dipole
A dipole is a pair of equal and opposite electric charges, +q and −q, separated by a fixed distance, with a dipole moment directed from the negative to the positive charge.
Dipole and sextupole magnets in accelerators
Dipole and sextupole magnets are members of the multipole family used in every synchrotron: dipoles with two poles bend the beam, and sextupoles with six poles correct chromaticity.
Dipole radiation
Dipole radiation is the electromagnetic radiation emitted by an oscillating electric or magnetic dipole, the simplest radiating source, with no emission along the dipole axis.
Dipropylene glycol
Dipropylene glycol, also called oxydipropanol, is a liquid glycol mixture produced as a byproduct of propylene glycol manufacture, used chiefly as a low-odor solvent for fragrances and cosmetics.
Diquark
A diquark is a correlated pair of quarks inside a hadron, treated as a single building block in quantum chromodynamics, though it cannot exist in isolation.
Dirac delta function
The Dirac delta function, or unit impulse, is a mathematical object that is zero everywhere except at one point and integrates to one, rigorously defined as a distribution.
Dirac equation
The Dirac equation is a relativistic wave equation for spin-1/2 particles, written by Paul Dirac in 1928, whose negative-energy solutions predicted antimatter, confirmed in 1932.
Dirac fermion
A Dirac fermion is a quasiparticle in a crystal whose energy depends linearly on momentum near a Dirac point, as in graphene and topological insulators.
Dirac fluid
The Dirac fluid in graphene is a strongly interacting electron-hole plasma that forms near charge neutrality and violates the Wiedemann-Franz law, first observed in 2016.
Dirac magnon
A Dirac magnon is a bosonic spin-wave excitation in magnetically ordered crystals whose magnon bands cross linearly, the magnon analog of the Dirac cones of electrons in graphene.
Dirac neutrino
A Dirac neutrino is a massive neutrino that exists as a particle distinct from its antiparticle, in contrast to a Majorana neutrino, where neutrino and antineutrino are the same particle.
Dirac plasmons
Dirac plasmons are collective, quantized oscillations of charge carriers in materials with linear, Dirac-like band structure, such as graphene, topological-insulator surface states, and Dirac or Weyl semimetals, operating in the terahertz and mid-infrared ranges.
Dirac plasmons in topological insulators
Dirac plasmons in topological insulators are collective charge-density oscillations of the massless, spin-polarized surface electrons of 3D topological insulators, first observed in Bi2Se3 micro-ribbons and studied for terahertz devices.
Dirac semimetal
A Dirac semimetal is a 3D crystalline material whose conduction and valence bands touch at isolated Dirac points, where electrons disperse linearly like massless Dirac fermions.
Dirac vortex
A Dirac vortex is a topological defect in a two-dimensional lattice where a Dirac mass winds around a point, binding a robust localized zero mode.
Dirac–Fock method
The Dirac–Fock method is a self-consistent-field technique for calculating the electronic structure of atoms and molecules; the relativistic extension of Hartree–Fock, it has been widely applied since the 1970s.
Diradical
A diradical is a molecular species carrying two unpaired electrons, with singlet and triplet electronic states; IUPAC's example is propane-1,3-diyl, and dioxygen is a diradical.
Dirección General de Aguas (Chile)
The Dirección General de Aguas (DGA) is the Chilean state agency, created in 1969 under the Ministry of Public Works, that manages the country's continental waters.
Direct air capture
Direct air capture (DAC) is a chemical process that separates carbon dioxide from ambient air, storing it underground or using it in products like synthetic fuels.
Direct analysis in real time mass spectrometry
Direct analysis in real time mass spectrometry (DART-MS) is an ambient ionization technique that analyzes samples in open air within seconds, with no sample preparation.
Direct and indirect band gaps
Direct and indirect band gaps distinguish semiconductors whose band edges align in momentum space from those needing phonon help, which is why LEDs use gallium arsenide rather than silicon.