Ionization

Ionization means any process whereby one or more electrons from an atom or molecule such that the atom or the molecule as a positively charged ion (cation ) remains. The reverse process, in which an electron from a positively charged atom or molecule is captured is referred to as recombination.

A further form of ionization, which is relevant in particular in the chemical, the addition of electrons to a neutral atom or molecule, so that a negatively charged ion ( anion) is obtained.

Also can be carried out by addition of ion ( proton, cations, anions) ionization, such as in mass spectrometry.

Is the nucleus of an atom of the electron shell pushed out - for example by a fast neutron - it is thereby also to an ion. However, for this process is not customary notation ionization.

In the literature there are also words such as " acids that provide weak nucleophilic anion at ionization - such as HSO4 - of H2SO4 - that can be found in [ ... ] ". Thus, the elimination of a proton in an acid -base reaction can be subsumed under the term ionization in a broader sense.

Mechanisms

For various ionization processes can result in:

• Ionizing radiation (including, here, for example, accelerated electrons in a thyratron tube ) may impact ionization by electrons " knock out " from their binding sites. The released electrons can further ionize with sufficient energy in turn.
• In the field ionization electrons are achieved by a sufficiently strong electric field from its bond.
• Highly excited atoms can pass through autoionization independently in an ionized state.

Symbolic notations

Symbols, such as (e, 2 e ), (e, 3e ), ( γ, 2e ), etc. used - for describing the Stoßionisationsprozesses often - in analogy to the notation of nuclear reactions. This is the first in the parentheses characters for the projectile. After the comma, the free particles are produced ( in addition to the ionized atom and including the projectile, if this is not - is absorbed - as in the case of the photon ). " 2e " means, for example, that two free electrons leave the atom. In (e, 2e) a singly-ionized atom is generated so by collision of an electron with an atom at ( γ, 2e) produced a double- ionized atom by interaction of a photon with an atom.

Ionization energies

For all ionization processes that must be applied by atom or molecule energy for the separation of the electron ( ionization ). In the previous section, possible sources of this energy were called. Ionization energies are typically on the order of several electron volts ( eg, argon in the ground state: 15.7 eV). Ionization energies are dependent on the material to be ionized and its current state of excitation. So it becomes increasingly difficult, an ionized atoms or molecules to ionize further. The ionization energy increases exponentially with each to remove electron from the electron shell.

Plasma

A gas with a significant share of ions and free electrons at equal total amounts of positive and negative charge is called a plasma. Almost all of the visible matter in the universe is more or less strongly ionized.

Application Examples

Means ionizers ionized, ie electrically conductive air is used in the processing of products that can be charged electrostatically, such as film or paper rolls. Due to the conductivity of the air, the charge is reduced and eliminated as threats of the radio shock and attracting unwanted dust particles. The transport is facilitated.

" Level the ion content in natural environments and indoors:

• Close proximity to waterfalls 20000-70000 ions / cm ³
• In the mountains or near the sea 4000-10000 ions / cm ³
• On the outskirts, on meadows and fields in 1000-3000 ions / cc
• Inner city parks 400-600 ions / cm ³
• In the city and agglomeration 200-500 ions / cm ³
• In a ventilated or air-conditioned spaces 10-100 ions / cc "

These ion concentrations are measured with a Ionometer. In this case, the polarity, and the respective concentration of the ions can be determined. Usually the ratio of the natural polarity of ions is balanced with a slight tendency to be more positively charged ions in nature. The ion concentration depends on the geological nature, the geographical location and the weather conditions.

Ionised air is used for example in the food industry for pasteurization of beer and other beverages. In the beverage filling the bottle is blown with ionized air to kill microorganisms before Füllbeginn.

Ionizing radiation is used for industrial sterilization (eg of medical disposable products).

Adverse effects

Due to the ion production, free radicals, the chemical reactions and, inter alia, lead to the formation of ozone, nitrogen oxides and other pollutants. The ozone produced can affect the human respiratory system and promotes corrosion.