ion, ion- +


ionic semiconductor
1. A solid in which the electrical conductivity from the flow of ions predominates over that from the movement of electrons or holes.
2. A solid whose electrical conductivity is due primarily to the movement of ions rather than that of electrons and holes.
3. A semiconductor whose primary charge carriers are ions instead of electrons and holes.
ionic spectrum, spark spectrum
1. The spectrum produced by a spark discharging through a gas or vapor.

With metal electrodes, a spectrum of the metallic vapor is obtained.

ionic strength
The sum of the concentrations of all ions in a solution multiplied by the square of their charge.
ionic strength principle
The concept that the amount of ionic activity in an electrolytic solution is based on the charge on the ions present rather than on their particular chemical natures.
ionic tweeter
A type of speaker in which a varying electrostatic field activates a mass of air ionized by a high-voltage radio-frequency field.

Ionic speakers are capable of extremely extended high-frequency response (up to 100 kHz or so) because of the extreme lightness of the ionic "diaphragm".

ionic-heated cathode, ionic heated cathode
A hot cathode heated primarily by ionic bombardment of the emitting surface.
1. The ionic characteristics of a solid.
2. Relating to, existing as, or characterized by ions (ionic gases, the ionic charge).
3. Based on or functioning by means of ions.
A naturally occurring radioactive isotope of the chemical element thorium.
1. The process of adding an electron to, or removing an electron from, an atom or molecule so as to give a negative or positive net charge.

The atom is then called an ion.

2. A process in which electrically neutral atoms or molecules are converted to electrically charged atoms or molecules (ions) by the removal or addition of negatively charged electrons.

It is one of the principal ways in which radiation transfers energy to matter, and hence of detecting radiation.

In general, ionization occurs whenever sufficiently energetic charged particles or radiant energy travels through gases, liquids, or solids.

A certain minimal level of ionization is present in the earth's atmosphere because of continuous absorption of cosmic rays from space and ultraviolet radiation from the sun.

3. The process by which a neutral atom, or a cluster of such atoms, becomes an ion.

This may occur, for instance, by absorption of light ("photoionization") or by a collision with a fast particle ("impact ionization").


4. Production of charged atoms or molecules in a gas by electric discharge or by irradiation.
ionization arc-over
1. Arcing across terminals or contacts due to ionization of the adjacent air or gas.
2. Arcing across satellite antenna terminals as the satellite passes through the ionized regions of the ionosphere.
3. An electric spark which is created when ionized charges build up in a medium and produce forces on the electrons.
ionization chamber
1. A device that measures the intensity of ionizing radiation.
2. A device used to detect and measure ionizing radiation, consisting of a gas-filled tube with electrodes at each end between which a voltage is maintained.

Radiation that ionizes gas molecules in the tube causes a current between the electrodes, the strength of which is a function of the radiation's intensity.

3. A gas-filled enclosure fitted with electrodes between which electric current flows upon ionization of the gas by incident radiation, the electrodes being maintained at a potential difference just sufficient to collect ions thus produced without causing further ionization.
4. The device for the detection and measurement of ionizing radiation.


When ionizing radiation; such as, a photon, enters the chamber (through a foil-covered window), it ionizes one or more gas molecules.



Geiger-Müller counter





—Compiled from "ionization chamber", Encyclopædia Britannica; 2010;
Encyclopædia Britannica Online; May 22, 2010.
ionization coefficient, specific ionization
The number of ion pairs formed per unit distance along the track of an ion passing through matter.
ionization constant
1. Analog of the dissociation constant; used for the application of the law of mass action to ionization.
2. An equilibrium constant for the ionization of a weak electrolyte.
3. A constant that depends upon the equilibrium between the ions and the molecules that are not ionized in a solution or liquid.
ionization cross section
1. The cross section for a particle or photon to undergo a collision with an atom, and so removing or adding one or more electrons to the atom.
2. An area in which the probability that an atom or ion will undergo ionization when it collides with a particle or photon of sufficient energy is measured.
ionization current, gas current
1. A current produced in an ionized gas by an electric field.
2. A positive-ion current produced by collisions between electrons and residual gas molecules in an electron tube.
