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[[File:Jablonski Diagram of Fluorescence Only-en.svg|thumb|[[Jablonski diagram]] shows the energy levels in a fluorescing atom in a phosphor. An electron in the phosphor absorbs a high-energy [[photon]] from the applied radiation, exciting it to a higher energy level. After losing some energy in non-radiative transitions, it eventually transitions back to its ground state energy level by fluorescence, emitting a photon of lower energy in the visible light region.]]
 
The scintillation process in inorganic materials is due to the [[electronic band structure]] found in the [[crystal]]s. An incoming particle can excite an electron from the [[valence band]] to either the [[conduction band]] or the [[exciton]] band (located just below the conduction band and separated from the valence band by an [[energy gap]]). This leaves an associated [[electron hole|hole]] behind, in the valence band. Impurities create electronic levels in the [[forbidden gap]].

The excitons are loosely bound [[electron–hole pair]]s that wander through the [[crystal lattice]] until they are captured as a whole by impurity centers. The latterThey then rapidly de-excite by emitting scintillation light (fast component).

In the caseconduction of inorganic [[scintillator]]sband, the activator impuritieselectrons are typicallyindependent chosenof sotheir that the emitted light is in the visible range or [[near ultraviolet|near-UV]], where [[photomultiplier]]s are effective. Theassociated holes associated with electrons in the conduction band are independent from the latter. Those holeselectrons and electronsholes are captured successively by impurity centers exciting certain [[metastable state]]s not accessible to the excitons. The delayed de-excitation of those metastable impurity states, slowed by reliance on the low-probability [[forbidden mechanism]], again results in light emission (slow component).
In the case of inorganic [[scintillator]]s, the activator impurities are typically chosen so that the emitted light is in the visible range or [[near ultraviolet|near-UV]], where [[photomultiplier]]s are effective.
 
Phosphors are often [[transition-metal]] compounds or [[rare-earth]] compounds of various types. In inorganic phosphors, these inhomogeneities in the crystal structure are created usually by addition of a trace amount of [[dopant]]s, impurities called ''[[activator (phosphor)|activators]]''. (In rare cases [[dislocation]]s or other [[crystal defect]]s can play the role of the impurity.) The wavelength emitted by the emission center is dependent on the atom itself and on the surrounding crystal structure.
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ZnS:Cu was the first formulation successfully displaying electroluminescence, tested at 1936 by [[Georges Destriau]] in Madame Marie Curie laboratories in Paris.
 
Powder or AC electroluminescence is found in a variety of backlight and night light applications. Several groups offer branded EL offerings (e.g. '''IndiGlo''' used in some Timex watches) or "Lighttape", another trade name of an electroluminescent material, used in electroluminescent [[light strips]]. The Apollo space program is often credited with being the first significant use of EL for backlights and lighting.<ref>{{cite web |url=https://www.hq.nasa.gov/alsj/tnD7290Lighting.pdf |title=ArchivedApollo copyLunar Surface Journal |access-date=2017-02-12 |url-status=live |archive-url=https://web.archive.org/web/20161221230335/http://www.hq.nasa.gov/alsj/tnD7290Lighting.pdf |archive-date=2016-12-21 }}</ref>
 
===White LEDs===
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|P10
| KCl
| greenGreen-absorbing [[scotophor]]
| –
| –
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|P13
| MgSi<sub>2</sub>O<sub>6</sub>:Mn
| Reddish Orange-Reddish Orange
| 640 nm
| –
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|P16
| CaMgSi<sub>2</sub>O<sub>6</sub>:Ce
| Bluish PurpleBlue-Bluish Purple
| 380 nm
| –
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|P18
| CaMgSi<sub>2</sub>O<sub>6</sub>:Ti, BeSi<sub>2</sub>O<sub>6</sub>:Mn
| White
| white-white
| 545,405 nm
| –
Line 349 ⟶ 354:
|P20, KA
| (Zn,Cd)S:Ag or (Zn,Cd)S:Cu
| Yellow-greenGreen
| 555 nm
| –
Line 375 ⟶ 380:
|-
|P22G
| ZnS(Zn,Cd)S:Cu,Al
| Green
| 530 nm
Line 412 ⟶ 417:
|P25
| CaSi<sub>2</sub>O<sub>6</sub>:Pb:Mn
| Orange-Orange
| 610 nm
| –
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|P27
| ZnPO<sub>4</sub>:Mn
| Reddish Orange-Reddish Orange
| 635 nm
| –
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|P35
| ZnS,ZnSe:Ag
| Blue White-Blue White
| 455 nm
| –
Line 520 ⟶ 525:
|P43, GY
| [[Gadolinium oxysulfide|Gd<sub>2</sub>O<sub>2</sub>S]]:Tb
| Yellow-greenGreen
| 545 nm
| –
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|P53, KJ
| [[Yttrium aluminium garnet|Y<sub>3</sub>Al<sub>5</sub>O<sub>12</sub>]]:Tb
| Yellow-greenGreen
| 544 nm
| –
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|
| Y<sub>3</sub>(Al,Ga)<sub>5</sub>O<sub>12</sub>:Tb
| Yellow-greenGreen
| 544 nm
| –
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|
|[[Indium borate|InBO<sub>3</sub>]]:Tb
| Yellow-greenGreen
| 550 nm
| –
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|
|[[magnesium tungstate|MgWO<sub>4</sub>]]
|Pale Blue
|Blue pale
|473 nm
|118 nm
Line 916 ⟶ 921:
|
| (Ca,Zn,Mg)<sub>3</sub>(PO<sub>4</sub>)<sub>2</sub>:Sn
| Orange-pinkPink
|610 nm
|146 nm
Line 934 ⟶ 939:
|
| (Sr,Mg)<sub>3</sub>(PO<sub>4</sub>)<sub>2</sub>:Sn
| Light Orange-pinkish whitePink
|626 nm
|120 nm
Line 1,142 ⟶ 1,147:
===Various===
Some other phosphors commercially available, for use as [[X-ray]] screens, [[neutron detector]]s, [[alpha particle]] [[scintillator]]s, etc., are:
{| class="wikitable"
*'''Gd<sub>2</sub>O<sub>2</sub>S:Tb''' ('''P43'''), green (peak at 545&nbsp;nm), 1.5 ms decay to 10%, low afterglow, high X-ray absorption, for X-ray, neutrons and gamma
|+
*'''Gd<sub>2</sub>O<sub>2</sub>S:Eu''', red (627&nbsp;nm), 850 μs decay, afterglow, high X-ray absorption, for X-ray, neutrons and gamma
!Phosphor
*'''Gd<sub>2</sub>O<sub>2</sub>S:Pr''', green (513&nbsp;nm), 7 μs decay, no afterglow, high X-ray absorption, for X-ray, neutrons and gamma
![[Chemical formula|Composition]]
*'''{{chem2|Gd2O2S:Pr,Ce,F}}''', green (513&nbsp;nm), 4 μs decay, no afterglow, high X-ray absorption, for X-ray, neutrons and gamma
!Color
*'''Y<sub>2</sub>O<sub>2</sub>S:Tb''' ('''P45'''), white (545&nbsp;nm), 1.5 ms decay, low afterglow, for low-energy X-ray
![[Wavelength]]
*'''Y<sub>2</sub>O<sub>2</sub>S:Eu''' ('''P22R'''), red (627&nbsp;nm), 850 μs decay, afterglow, for low-energy X-ray
!Decay
*'''Y<sub>2</sub>O<sub>2</sub>S:Pr''', white (513&nbsp;nm), 7 μs decay, no afterglow, for low-energy X-ray
!Afterglow
*'''{{chem|Zn|0.5|Cd|0.4|S:Ag}}''' ('''HS'''), green (560&nbsp;nm), 80 μs decay, afterglow, efficient but low-res X-ray
!X-ray absorption
*'''{{chem|Zn|0.4|Cd|0.6|S:Ag}}''' ('''HSr'''), red (630&nbsp;nm), 80 μs decay, afterglow, efficient but low-res X-ray
!Usage
*'''CdWO<sub>4</sub>''', blue (475&nbsp;nm), 28 μs decay, no afterglow, intensifying phosphor for X-ray and gamma
|-
*'''CaWO<sub>4</sub>''', blue (410&nbsp;nm), 20 μs decay, no afterglow, intensifying phosphor for X-ray
|
*'''MgWO<sub>4</sub>''', white (500&nbsp;nm), 80 μs decay, no afterglow, intensifying phosphor
*|'''YGd<sub>2</sub>SiOO<sub>52</sub>S:Ce''' ('''P47Eu'''), blue (400&nbsp;nm), 120 ns decay, no afterglow, for electrons, suitable for photomultipliers
|Red
*'''YAlO<sub>3</sub>:Ce''' ('''YAP'''), blue (370&nbsp;nm), 25 ns decay, no afterglow, for electrons, suitable for photomultipliers
|627 nm
*'''Y<sub>3</sub>Al<sub>5</sub>O<sub>12</sub>:Ce''' ('''YAG'''), green (550&nbsp;nm), 70 ns decay, no afterglow, for electrons, suitable for photomultipliers
|850 μs
*'''{{chem2|Y3(Al,Ga)5O12:Ce}}''' ('''YGG'''), green (530&nbsp;nm), 250 ns decay, low afterglow, for electrons, suitable for photomultipliers
|Yes
*'''CdS:In''', green (525&nbsp;nm), <1 ns decay, no afterglow, ultrafast, for electrons
|High
*'''ZnO:Ga''', blue (390&nbsp;nm), <5 ns decay, no afterglow, ultrafast, for electrons
|X-ray, neutrons and gamma
*'''ZnO:Zn''' ('''P15'''), blue (495 nm), 8 μs decay, no afterglow, for low-energy electrons
|-
*'''{{chem2|(Zn,Cd)S:Cu,Al}}''' ('''P22G'''), green (565&nbsp;nm), 35 μs decay, low afterglow, for electrons
|
*'''{{chem2|ZnS:Cu,Al,Au}}''' ('''P22G'''), green (540&nbsp;nm), 35 μs decay, low afterglow, for electrons
|'''Gd<sub>2</sub>O<sub>2</sub>S:Pr'''
*'''{{chem2|ZnCdS:Ag,Cu}}''' ('''P20'''), green (530&nbsp;nm), 80 μs decay, low afterglow, for electrons
|Green
*'''ZnS:Ag''' ('''P11'''), blue (455 nm), 80 μs decay, low afterglow, for alpha particles and electrons
|513 nm
*'''[[anthracene]]''', blue (447 nm), 32 ns decay, no afterglow, for alpha particles and electrons
|4 μs
*plastic ('''EJ-212'''), blue (400 nm), 2.4 ns decay, no afterglow, for alpha particles and electrons
|No
*'''Zn<sub>2</sub>SiO<sub>4</sub>:Mn''' ('''P1'''), green (530&nbsp;nm), 11 ms decay, low afterglow, for electrons
|High
*'''ZnS:Cu''' ('''GS'''), green (520 nm), decay in minutes, long afterglow, for X-rays
|X-ray, neutrons and gamma
*'''[[sodium iodide|NaI]]:Tl''', for X-ray, alpha, and electrons
|-
*'''[[Caesium iodide|CsI]]:Tl''', green (545 nm), 5 μs decay, afterglow, for X-ray, alpha, and electrons
|
*'''<sup>6</sup>[[lithium fluoride|LiF]]/ZnS:Ag''' ('''ND'''), blue (455&nbsp;nm), 80 μs decay, for [[thermal neutron]]s
|'''{{chem2|Gd2O2S:Pr,Ce,F}}'''
*'''{{chem2|^{6}LiF/ZnS:Cu,Al,Au}}''' ('''NDg'''), green (565&nbsp;nm), 35 μs decay, for [[neutron]]s
|Green
*Cerium doped YAG phosphor, yellow, used in white [[LED]]s for turning blue to white light with a broad spectrum of light
|513 nm
|7 μs
|No
|High
|X-ray, neutrons and gamma
|-
|
|'''Y<sub>2</sub>O<sub>2</sub>S:Pr'''
|White
|513 nm
|7 μs
|No
|
|Low-energy X-ray
|-
|HS
|'''{{chem|Zn|0.5|Cd|0.4|S:Ag}}'''
|Green
|560 nm
|80 μs
|Yes
|
|Efficient but low-res X-ray
|-
|HSr
|'''{{chem|Zn|0.4|Cd|0.6|S:Ag}}'''
|Red
|630 nm
|80 μs
|Yes
|
|Efficient but low-res X-ray
|-
|
|'''CdWO<sub>4</sub>'''
|Blue
|475 nm
|28 μs
|No
|
|Intensifying phosphor for X-ray and gamma
|-
|
|'''CaWO<sub>4</sub>'''
|Blue
|410 nm
|20 μs
|No
|
|Intensifying phosphor for X-ray and gamma
|-
|
|'''MgWO<sub>4</sub>'''
|White
|500 nm
|80 μs
|No
|
|Intensifying phosphor
|-
|YAP
|'''YAlO<sub>3</sub>:Ce'''
|Blue
|370 nm
|25 ns
|No
|
|For electrons, suitable for photomultipliers
|-
|YAG
|'''Y<sub>3</sub>Al<sub>5</sub>O<sub>12</sub>:Ce'''
|Green
|550 nm
|70 ns
|No
|
|For electrons, suitable for photomultipliers
|-
|YGG
|'''{{chem2|Y3(Al,Ga)5O12:Ce}}'''
|Green
|530 nm
|250 ns
|Low
|
|For electrons, suitable for photomultipliers
|-
|
|'''CdS:In'''
|Green
|525 nm
|<1 ns
|No
|
|Ultrafast, for electrons
|-
|
|'''ZnO:Ga'''
|Blue
|390 nm
|<5 ns
|No
|
|Ultrafast, for electrons
|-
|
|'''[[Anthracene]]'''
|Blue
|447 nm
|32 ns
|No
|
|For alpha particles and electrons
|-
|
|plastic ('''EJ-212''')
|Blue
|400 nm
|2.4 ns
|No
|
|For alpha particles and electrons
|-
|P1
|'''Zn<sub>2</sub>SiO<sub>4</sub>:Mn'''
|Green
|530 nm
|11 ns
|Low
|
|For electrons
|-
|GS
|'''ZnS:Cu'''
|Green
|520 nm
|Minutes
|Long
|
|For X-rays
|-
|
|'''[[sodium iodide|NaI]]:Tl'''
|
|
|
|
|
|For X-ray, alpha, and electrons
|-
|
|'''[[Caesium iodide|CsI]]:Tl'''
|Green
|545 nm
|5 μs
|Yes
|
|For X-ray, alpha, and electrons
|-
|ND
|'''<sup>6</sup>[[lithium fluoride|LiF]]/ZnS:Ag'''
|Blue
|455 nm
|80 μs
|
|
|For [[thermal neutron]]s
|-
|NDg
|'''{{chem2|^{6}LiF/ZnS:Cu,Al,Au}}'''
|Green
|565 nm
|35 μs
|
|
|For neutrons
|-
|
|Cerium doped YAG phosphor
|Yellow
|
|
|
|
|
|}
*
*
*
*
*
*
*
 
==See also==
Retrieved from "https://en.wikipedia.org/wiki/Phosphor"