Fr.: particule d'échange
In quantum field theory, a particle that transfers momentum and energy between interacting objects, and is said to mediate the interaction. All four of the fundamental forces involve the exchange of one or more particles. For example, photon is the exchange particle of the electromagnetic force.
Chemistry: A complex formed from combination of a molecule with another molecule of the same type but in an → excited state. In other words, a → dimer in an electronically excited state. See also → exciplex.
For a → triangle with two sides extended in the direction opposite their common → vertex, a circle that lies outside the triangle and is tangent to the three sides (two of them extended). The center of the excircle, called the → excenter, is the point of intersection of the bisector of the interior angle and the bisector of the exterior angles at the other two vertices.
To cut out or off; to remove
The act of removal; an excising. The surgical removal of a foreign body or of tissue.
Verbal noun of → excise.
1) The addition of → energy to an → atomic
or → molecular system, → transferring it
from its → ground state to an
→ excited state.
Fr.: énergie d'excitation
Fr.: potentiel d'excitation
Fr.: température d'excitation
Of a gas or plasma, the temperature deduced from the → populations of atomic → excited states, as expressed by the Boltzmann formula: Nu/Nl = (gu/gl) exp (-ΔE/kTex), where Nu and Nl are the upper level and lower level populations respectively, gu and gl the statistical weights, ΔE = hν the energy difference between the states, k is → Boltzmann's constant, and h→ Planck's constant. The higher the energy of the occupied states, the higher the excitation temperature.
Verb of → excitation.
From L. excitare "to rouse, produce," freq. of exciere "to call forth, instigate," from → ex- "out" + ciere "to move, set in motion;" PIE base *kei- "to move to and fro" (cf. Av. šiyav-, š(ii)auu- "to move, go," šiyavati "goes," šyaoθna- "activity; action; doing, working;" O.Pers. šiyav- "to go forth, set," ašiyavam "I set forth;" Mod.Pers. šodan, šow- "to go; to become;" cf. Skt. cyu- "to move to and fro, shake about; to stir," cyávate "stirs himself, goes;" Gk. seuo "I start quickly after," kinein "to move;" Goth. haitan "call, be called;" O.E. hatan "command, call").
Barangixtan, from intensive prefix bar- "on, upon, up," → on-, + angixtan, angizidan "to excite, stimulate," from Mid.Pers. hangêxtan, hangêz- "to arouse, stimulate, stir up," from Proto-Iranian *hamgaiz-, from ham-, → com-, + *gaiz- "to disturb, stir, excite." The Mod.Pers. gij, giž "confused, astonished, dizzy" is from this stem (Cheung 2007).
atom-e barangixté (#)
Fr.: atome excité
An atom in which one or more of its bound electrons are at → energy levels higher than their normal level.
hâlat-e barangixté (#)
Fr.: état excité
The condition of a particle or system of particles (especially an atom, nucleus, molecule) after absorbing energy from outside and transiting to a higher → energy level than that of its → ground state. Excited states are transitory as they lose energy through emissions or collisions and return to ground state.
Fr.: étoile excitatrice
To shut or keep out; to hinder from being included, considered, or accepted. → exclusion.
An act or instance of excluding; the state of being excluded.
Verbal noun of → exclude.
Fr.: principe d'exclusion
Excluding or having power to exclude; excluding all else; rejecting other considerations, possibilities, etc.
Adj. from → exclude.
Fr.: disque d'excrétion
An expanding → equatorial → disk or → torus of material ejected by a star. The phenomenon may result from a stellar → merger or an increase in its rate of → rotation or → stellar winds. Contrasted with → accretion disk.