[Jack]

My daughter has stars on her ceiling that glow in the dark. Cool. Understandable.  But, only if enough light has previously "loaded them up".  Question:  Is such a chemical event controlable?  For example, is there a gas, or chemical compound that, when "bombarded" with an outside energy soure (such as microwave, ultrasound, high-pitch sound, etc) will glow upon receipt of this outside energy source, on command?

[hmx9123]

There's a number of chemical compounds like this, one of the most notable being luminol.  When it is oxidized, it releases light, much in the same way a firefly does.  The stars on the ceiling use a different method of light emission I think, so maybe someone else here has a better idea about them.

[AWK]

The stars on the ceiling use pure physical phenomenon called phosphorescence.

From Wikipedia, the free encyclopedia (http://en.wikipedia.org/wiki/Phosphorescence)

Phosphorescence is a radiative transition involving a change in the spin multiplicity of a molecule. Because of this change the radiative transition is delayed and the phosphorescent material glows a while after the incident illumination stops.

[One Armed Scissor]

Emission of light following absorption of radiation. Emitted light is of longer wavelength than the exciting radiation and is a result of decay of electrons from the triplet to the ground state. Lasts longer than fluorescence (electron decay from singlet to ground state) and occurs after a longer delay.

The compound used in those is likely either zinc sulfide or strontium aluminate, with ZnS being the more common one. (interesting that the phosphorencing compound contains no phosphorus :p it probably comes from the word "phosphors" which relates to these compounds that emit photons after being excited e.g. on your TV screen.)

[jdurg]

Actually, phosphorescence is from the greek language meaning "emitting light," or something to that effect.  The name phosphorus was given to that element because when it was discovered as the white allotrope, it gave off light due to its reaction with oxygen.  So the name phosphorescence has nothing to do with the element phosphorus.  It actually has to do with the emission of light.  

[Gerard]

My daughter has stars on her ceiling that glow in the dark. Cool. Understandable.  But, only if enough light has previously "loaded them up".  Question:  Is such a chemical event controlable?  For example, is there a gas, or chemical compound that, when "bombarded" with an outside energy soure (such as microwave, ultrasound, high-pitch sound, etc) will glow upon receipt of this outside energy source, on command?

geneticist today just experimented with the lucifarse enzyme injecting that protein to some tobacco plat and the results were great!
luminous plants!

[mir]

geneticist today just experimented with the lucifarse enzyme injecting that protein to some tobacco plat and the results were great!
luminous plants!

I have worked with Luciferin and Luciferase from fireflies :-D
We where counting bacterias, by destroying the cells, injecting Luciferin and Luciferase, and then count photons released in the reaction with the bacterias ATP. We had to be careful not stress the bacterias to much, or else they used much of their ATP and gave false readings :-)

The most amazing thing is, that to get the protein they still have to catch fireflies, extract the protein and isolate it. The old fashion way :-)

[P]

Actually, phosphorescence is from the greek language meaning "emitting light," or something to that effect.  The name phosphorus was given to that element because when it was discovered as the white allotrope, it gave off light due to its reaction with oxygen.  So the name phosphorescence has nothing to do with the element phosphorus.  It actually has to do with the emission of light.  

Pretty certain that's why phosphorous is called that  -  because it phosphoresces.

The delay in the emition of the radiation is because of these triplet states that 'one armed scissor' pointed out  -  they are classed as 'Metasatable states'  because they are (even though in an excited state) fairly stable, which is why it takes longer for the energy to be released and thus the light emission carries on for longer.

[Yggdrasil]

Pretty certain that's why phosphorous is called that  -  because it phosphoresces.

Phosphorus does not phosphoresce, it luminesces.  The glow of white phosphorus is not due to the absorbtion and re-emission of photons, but rather from a light-producing reaction with oxygen.

http://en.wikipedia.org/wiki/Phosphorus#Glow

[P]

Terribly sorry!  Did not know about the reation with oxygen at certain partial presures.  I thought it was phosphorescence.