Ionization is the physical process of converting an
atomor moleculeinto an ionby adding or removing charged particles such as electrons or other ions.
This process works slightly differently depending on whether an ion with a positive or a negative
electric chargeis being produced. A positively charged ion is produced when an electron bonded to an atom (or molecule) absorbs enough energy to escape from the electric potentialbarrier that originally confined it, thus breaking the bond and freeing it to move. The amount of energy required is called the ionization potential. A negatively charged ion is produced when a free electron collides with an atom and is subsequently caught inside the electric potential barrier, releasing any excess energy.
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.
classical physicsand the Bohr modelof 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.
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 stateuntil the energy absorbed is radiated out and the electron re-enters the lowest available state.
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.
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 mechanicsionization 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.
Tunnel ionizationis 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.
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.
Photoionizationand Photoionization mode
Quantum tunnelingfor detailed treatment of how tunneling works.
Real Life Applications of Ions
*Ions are a key element of
ion thrusterswhich are a possible method to be used in powering space craft.
Trapped ion quantum computers are quantum computerswhich use suspended ions for data storage and calculations.
* Detergent-free washer balls based on ionisation of oxygen molecules in the washing water
* Drinking alkaline ionised water (from a water ioniser in your kitchen sink) is claimed to have several health benefits
Other uses of ions
Ion Cannonis an idea currently in the realm of science fiction that would use beams of ionized atoms as a weapon. Classed as a particle beam weaponand superweapon.
* 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. PDFlink|http://www.clf.rl.ac.uk/Reports/2004-2005/pdf/26.pdf|217 KiB
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См. также в других словарях:
Ionization — I on*i*za tion, n. (Elec. Chem.) the process of converting neutral atoms or molecules into ions. The process may occur by dissolving an ionic substance in a dissociating solvent, such as water, or by adding or subtracting an electron to or from… … The Collaborative International Dictionary of English
ionization — ionization. См. ионизация. (Источник: «Англо русский толковый словарь генетических терминов». Арефьев В.А., Лисовенко Л.А., Москва: Изд во ВНИРО, 1995 г.) … Молекулярная биология и генетика. Толковый словарь.
Ionization — См. Ионизация Термины атомной энергетики. Концерн Росэнергоатом, 2010 … Термины атомной энергетики
ionization — 1891; see IONIZE (Cf. ionize) + ATION (Cf. ation) … Etymology dictionary
ionization — (Amer.) iÂ·onÂ·iÂ·zaÂ·tion || â€šaÉªÉ™nÉ™ zeÉªÊƒn / naÉª z n. process of separating or changing into ions; production of ions in a solution (also ionisation) … English contemporary dictionary
ionization — i·on·i·za·tion (ī ə nĭ zāʹshən) n. 1. The formation of or separation into ions by heat, electrical discharge, radiation, or chemical reaction. 2. The state of being ionized. * * * Process by which electrically neutral atoms or molecules are… … Universalium
ionization — jonizacija statusas T sritis automatika atitikmenys: angl. ionization vok. Ionisation, f rus. ионизация, f pranc. ionisation, f … Automatikos terminų žodynas
ionization — jonizavimas statusas T sritis automatika atitikmenys: angl. ionization; ionizing vok. Ionisierung, f rus. ионизация, f; ионизирование, n pranc. ionisation, f … Automatikos terminų žodynas
ionization — jonizacija statusas T sritis Standartizacija ir metrologija apibrėžtis Atomų arba molekulių virtimas jonais. atitikmenys: angl. ionization vok. Ionisation, f rus. ионизация, f pranc. ionisation, f … Penkiakalbis aiškinamasis metrologijos terminų žodynas
ionization — jonizacija statusas T sritis chemija apibrėžtis Atomų arba molekulių virtimas jonais. atitikmenys: angl. ionization rus. ионизация … Chemijos terminų aiškinamasis žodynas