03-14-2023-1516 - phosphor continued...

P21

MgF2:Mn2+

Reddish

605 nm

–

–

CRT, Radar

Registered by Allen B DuMont Laboratories

P23

ZnS:Ag+(Zn,Cd)S:Ag

White

575,460 nm

–

Short

CRT, Direct viewing television

Registered by United States Radium Corporation.

 

https://en.wikipedia.org/wiki/Phosphor

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 The holes associated with electrons in the conduction band are independent from the latter. Those holes and electrons are captured successively by impurity centers exciting certain metastable states 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).

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 dopants, impurities called activators. (In rare cases dislocations or other crystal defects 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. 

https://en.wikipedia.org/wiki/Phosphor

 

https://en.wikipedia.org/wiki/Scintillator

https://en.wikipedia.org/wiki/Phosphorescence