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Encyclopedia > Ionization

Ionization is the physical process of converting an atom or molecule into an ion by changing the difference between the number of protons and electrons. This process works slightly differently depending on whether an ion with a positive or a negative electric charge is being produced. A positive electric charge is produced when an electron bound to an atom or molecule absorbs enough energy from an external source to escape from the electric potential barrier that originally confined it. The amount of energy required being equal to the Ionization potential. A negative electric charge is produced when a free electron collides with an atom and is subsequently caught inside the electric potential barrier, releasing any excess energy. Physics (Greek: (phúsis), nature and (phusiké), knowledge of nature) is the science concerned with the discovery and understanding of the fundamental laws which govern matter, energy, space, and time and explaining them using mathematics. ... “Atomic” redirects here. ... In chemistry, a molecule is an aggregate of two or more atoms in a definite arrangement held together by chemical bonds [1] [2] [3] [4] [5]. Chemical substances are not infinitely divisible into smaller fractions of the same substance: a molecule is generally considered the smallest particle of a pure... “Multivalent” redirects here. ... // Properties [1][2] In physics, the proton (Greek proton = first) is a subatomic particle with an electric charge of one positive fundamental unit (1. ... e- redirects here. ... Electric charge is a fundamental conserved property of some subatomic particles, which determines their electromagnetic interaction. ... Electric potential is the potential energy per unit of charge associated with a static (time-invariant) electric field, also called the electrostatic potential, typically measured in volts. ... The ionization potential, or ionization energy, of an atom or molecule is the energy required to strip it of an electron. ...


Ionization can generally be broken down into two types: Sequential Ionization and Non-Sequential Ionization. In classical physics, only Sequential Ionization can take place and therefore refer to the Classical Ionization section for more information. Non-Sequential Ionization violates several laws of classical physics and thus will be discussed in more detail in the Quantum Ionization section.

Contents

Classical Ionization

Applying only classical physics and the Bohr model of the atom makes both atomic and molecular ionization entirely deterministic, that is every problem will always have a definite and computable answer. According to classical physics it is absolutely necessary that the energy of the electron exceeds the energy difference of the potential barrier it is trying to pass. Conceptually this idea should make sense: the same way a person can not jump over a one meter wall without jumping at least one meter off the ground, an electron can not get over a 13.6 eV potential barrier without at least 13.6 eV of energy. Classical physics is physics based on principles developed before the rise of quantum theory, usually including the special theory of relativity and general theory of relativity. ... The Bohr model of the hydrogen atom, where negatively charged electrons confined to atomic shells encircle a small positively charged atomic nucleus, and that an electron jump between orbits must be accompanied by an emitted or absorbed amount of electromagnetic energy hν. The orbits that the electrons travel in are... Physicists have sometimes used the term determinism in a special way that people such as Karl Popper and Stephen Hawking have called scientific determinism. ... The electronvolt (symbol eV, or, rarely and incorrectly, ev) is a unit of energy. ...


Applying to positive ionization

According to these two principles, the energy required to release an electron is strictly greater than or equal to the potential difference between the current bound atomic or molecular orbital and the highest possible orbital. If the energy absorbed exceeds this potential, then the electron is emitted as a free electron. Otherwise, the electron briefly enters an excited state until the energy absorbed is radiated out and the electron re-enters the lowest available state. In chemistry, an atomic orbital is the region in which an electron may be found around a single atom. ... It has been suggested that this article or section be merged with quantum state. ... Radiation in physics is the process of emitting energy in the form of waves or particles. ...


Applying to negative ionization

Due to the shape of the potential barrier, according to these principles a free electron must have an energy greater than or equal to that of the potential barrier in order to make it over. If it has enough energy to do so, it will be bound to the lowest available energy state, and the remaining energy will be radiated away. If the electron does not have enough energy to surpass the potential barrier, then it is forced away by the electrostatic force, described by Coulombs Law, associated with the electric potential barrier. Coulombs torsion balance In physics, Coulombs law is an inverse-square law indicating the magnitude and direction of electrostatic force that one stationary, electrically charged object of small dimensions (ideally, a point source) exerts on another. ...


Sequential Ionization

Sequential ionization is basically a description of how the ionization of an atom or molecule takes place. More specifically, it means that an ion with a +2 charge can only be created from an ion with a +1 charge or a +3 charge. That is, the numerical charge of an atom or molecule must change sequentially, always moving from one number to an adjacent, or sequential number.


Quantum Ionization

In quantum mechanics ionization can still happen classically where the electron has enough energy to make it over the potential barrier, but there is the additional possibility of tunnel ionization. Fig. ... Tunnel ionization is a process in which electrons in an atom (or a molecule) pass through the potential barrier and escape from the atom (or molecule). ...


Tunnel Ionization

Tunnel ionization is ionization due to quantum tunneling. In classical ionization an electron must have enough energy to make it over the potential barrier, but quantum tunneling allows the electron simply to go through the potential barrier instead of going all the way over it because of the wave nature of the electron. The probability of an electron tunneling through the barrier drops off exponentially with the width of the potential barrier. Therefore, an electron with a higher energy can make it further up the potential barrier, leaving a much thinner barrier to tunnel through and thus a greater chance to do so. Quantum tunneling is the quantum-mechanical effect of transitioning through a classically-forbidden energy state. ...


Non-Sequential Ionization

When the fact that the electric field of light is an alternating electric field is combined with tunnel ionization, the phenomenon of non-sequential ionization emerges. An electron that tunnels out from an atom or molecule may be sent right back in by the alternating field, at which point it can either recombine with the atom or molecule and release any excess energy, or it also has the chance to further ionize the atom or molecule through high energy collisions. This additional ionization is referred to as non-sequential ionization for two reasons: one, there is no order to how the second electron is removed, and two, an atom or molecule with a +2 charge can be created straight from an atom or molecule with a neutral charge, so the integer charges are not sequential. Non-sequential ionization is often studied at lower laser-field intensities, since most ionization events are sequential when the ionization rate is high.


See also

Tunnel ionization is a process in which electrons in an atom (or a molecule) pass through the potential barrier and escape from the atom (or molecule). ... Quantum tunneling is the quantum-mechanical effect of transitioning through a classically-forbidden energy state. ... ... The ionization potential, or ionization energy, of an atom or molecule is the energy required to strip it of an electron. ...

External References

  • Sequential Ionization of C60 with femtosecond laser pulses. The Journal of Chemical Physics -- January 22, 2001 -- Volume 114, Issue 4, pp. 1716-1719.
  • Can harmonic generation cause non-sequential ionization? J. Phys. B: At. Mol. Opt. Phys. 31 No 19 (14 October 1998) L841-L848.
  • Probing atomic ionization mechanisms in intense laser fields by calculating geometry and diffraction independent ionization probabilities. J Wood, E M L English, S L Stebbings, W A Bryan, W R Newell, J McKenna, M Suresh, B Srigengan, I D Williams, I C E Turcu, J M Smith, K G Ertel, E J Divall, C J Hooker, A J Langley. http://www.clf.rl.ac.uk/Reports/2004-2005/pdf/26.pdfPDF

  Results from FactBites:
 
SongMeanings | lyrics | Modest Mouse - She Ionizes And Atomizes (2028 words)
The song is about a guy who is apparently with a girl he doesn't feel love toward and is probably just using her for sex.
Then he notices this girl (who ionizes and atomizes), falls in love with her blah blah and notices how empty his relationship is. Fluorescent lights are just a part of real light and that's what his relationship is, part of real love, etc.
"she ionizes and atomizes then turns into sunlight"...."the real lights will make you heavy but never really empty flourescent light will always equal empty" hes saying shes the real thing, shes the sunlight and everything else is the flourescent light, empty.
Common Acids (269 words)
Acetic acid is classified as a weak acid since it ionizes weakly in water.
It is used for the "pickling" of steel to retard corrosion, in the refinement of petroleum, and in the manufacture of fertilizers.
Citric acid, found in citrus fruits, is classified as a weak acid since it ionizes weakly in water.
  More results at FactBites »

 
 

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