Phospor that glows under infrared exposure ?

[Externet]

Hello

What compound would glow when exposed to infrared light?

 

It is used applied as paint on a piece of cardboard to test the illumination from remote controls and infrared beams. Read it is some phosphor compound, but unsure if it is plain white phosphor with something else or not.

 

It is shown here:

http://img.alibaba.com/photo/10846815/Infrared__IR__Laser_Test_Card__Anti_stoke_.jpg

Thanks,

Miguel

[Tannin]

I admit that I don't know the answer, but I can propose a mechanism: multiphoton absorption of "small" IR quants and subsequent fluorescence (or phosporescence) of the one "big" quant in UV-Vis range.

For sufficiently high intensities, multiphoton absorption is not frequency selective. Also because we are not in the gas phase, but in the solid state, the upper level is actually a band.

It would be very interesting to learn from the expert which compound they actually use and it this is the mechanism.

[swansont]

The "IR" cards shown in your link work by activating them with visible light/UV first, which puts them in a metastable excited state. When the IR is intense enough you can observe the rapid depletion of the excited population; the dot will get very faint unless you move the card around. As Tannin notes, you need more than one IR photon if you were to do the interaction from the ground state, and there are cards that use that process.

[Externet]

Hi.

Investigating a little deeper, appears that the compound is ZnS with Cu or other dopants to select the color given off.

And seems the nasty habit of naming things wrong as "phosphors" when there is no phosphor at all strikes again. That pisses me off. Misleading information using the word phosphor when they should say plainly luminescent.

 

I do not have a plain old green monitor to aim my IR laser onto it and check if the CRT uses the same compound. But that works with electrons, not photons... I'll try on my oscilloscope.

 

The powder coating inside fluorescent lamp tubes, what is it, exactly? It gives off white light when irradiated with UV, IR, plasma, ions, electrons or by what from inside the tube?

 

EDIT- added-

Found this:

(Ba,Eu)Mg2Al16O27, blue phosphor for trichromatic fluorescent lamps

(Ce,Tb)MgAl11O19, green phosphor for trichromatic fluorescent lamps

(Y,Eu)2O3, red phosphor for trichromatic fluorescent lamps

(Sr,Eu,Ba,Ca)5(PO4)3Cl, blue phosphor for trichromatic fluorescent lamps

(La,Ce,Tb)PO4, green phosphor for trichromatic fluorescent lamps

 

And dopants added to ZnS, what is the doping process; is it just adding a minute amount of what Cu compound and mechanically mixing or something more elaborated?

 

Miguel

[John Cuthber]

"And seems the nasty habit of naming things wrong as "phosphors" when there is no phosphor at all strikes again. "

OK, what do you think a phosphor is?

[swansont]

IIRC phosphors continue to emit when the excitation ceases, and the materials in the IR cards I have seen qualify.