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LAMADUK

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Did you know that when a laser is shown at a glow stick for about 5 mins it actually makes the glow stick not light up anymore. When you crack them nothing happens? Can someone explain this?:yh:
 

Eudaimonium

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I have not observed this phenomenon before since I don't have any glowsticks, they are hard to get here.

Glow stick is composed of two parts, one being a chemical with base and TCPO as active ingredient, and a flourescent melted dye to give it color. The glass you break is a small ampule with high concentration Hydrogen Peroxyde (H2O2).

Hydrogen Peroxide is decomposing into water and oxigen, releasing energy in the process which in turn is converted into light by other chemicals.
Perhaps the laser is breaking down the Hydrogen Peroxide into water and oxigen before it gets a chance to mix with the rest of chemicals to produce light.
 
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I wonder if i would still fluoresce under a 405nm as the florescent dye is still in the stick:thinking:
 

Eudaimonium

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I wonder if i would still fluoresce under a 405nm as the florescent dye is still in the stick:thinking:
Yes but only that moment, it would not glow in the dark like those green caps do.
This is constant chemical reaction keeping it glowing , while in caps I think it's a phosphorus-based compound that aborbs the light, then slowly releases it (simplified explanation).

Not exactly sure, would be great if somebody explained detailed physics behind this.
 
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I sorta figured it would still light up under 405nm, but as You said with no internal energy source it can't continue after the laser is moved. I would be curious to know about the Cap Chemicals and how they work as well.

Wouldn't there be some indication if the laser was breaking down the H2O2 inside the vial?
 

millirad

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Yes, an interesting glow stick experiment. Oh, and welcome to the forum! Be sure to purchase some quality laser eye-wear and be cautious with lasers.
 
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Eudaimonium I know the peroxide is isolated in the vial, and that's where I was wondering if any action could be seen. I think I have some sticks somewhere which I'll try to find later today to experiment with. I will hit them with 405/532/650 to see what happens.
 

Eudaimonium

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Eudaimonium I know the peroxide is isolated in the vial, and that's where I was wondering if any action could be seen. I think I have some sticks somewhere which I'll try to find later today to experiment with. I will hit them with 405/532/650 to see what happens.
Wow, report back with your findings, just don't ruin all your glowsticks. I've seen the once, very cool fun stuff :)
 

JaiNobeZ

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What wavelength laser? Green, i'm assuming? They keep H2O2 in darkened bottles because light decomposes it. My guess is it's that. But on the other hand,
H2O2 --> H2O + O2 means there is an increase in volume. If enough of the H2O2 is decomposing to make the glowstick not light up anymore, surely it's almost all decomposing in which case wouldn't it have caused a volume increase enough to crack the vial? Idk... weird. Is it at all possible that the glowstick you were using was so old that it wouldn't work anyway? And have you tried this on numerous occaisions?

Eudaimonium, want me to send you some glowsticks? They're 25 for £1 here.
 

HIMNL9

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No, it's the TCPO based part that become decomposed from the UV part of the light, and stop to react with the H2O2, not the H2O2 that become decomposed.

This is also valid for the small amount of UV present in the ambient light, also if more slow process ..... in fact, if you unseal a glowstick from its lightproof pack and left it in ambient light for a week or two, it don't work anymore, when you break the H2O2 vial.

This reaction can be slowed down a lot from low temperatures, but is constant, once the fluorescent liquid is exposed to light, regardless the fact that the light is the one produced from the reaction or any external source.
 

Eudaimonium

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Eudaimonium, want me to send you some glowsticks? They're 25 for £1 here.
No thanks, I don't find much need for them anyhow. When I'll need some, I'll let you know :)
No, it's the TCPO based part that become decomposed from the UV part of the light, and stop to react with the H2O2, not the H2O2 that become decomposed.

This is also valid for the small amount of UV present in the ambient light, also if more slow process ..... in fact, if you unseal a glowstick from its lightproof pack and left it in ambient light for a week or two, it don't work anymore, when you break the H2O2 vial.

This reaction can be slowed down a lot from low temperatures, but is constant, once the fluorescent liquid is exposed to light, regardless the fact that the light is the one produced from the reaction or any external source.
Wait, does Hydrogen Peroxide decompose in the light naturaly?
Crap, better go seal my 1 liter bottle of (once was)35% H2O2.
 

HIMNL9

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Eudaimonium, H2O2 naturally decompose slowly, also if not left at light ..... better way to slow down this, is to keep it sealed.

Anyway, is not this that decompose in glow sticks, when exposed to light, is the rest ;)
 

Eudaimonium

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Eudaimonium, H2O2 naturally decompose slowly, also if not left at light ..... better way to slow down this, is to keep it sealed.

Anyway, is not this that decompose in glow sticks, when exposed to light, is the rest ;)
Well the bottle itself is sealed, it's just that it's in a corner of a room waiting usage, not in some box kept dark.

Should I shield it from the light to slow down the decomposition?
 




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