[quizzicalDude]

Hi there!
I have a problem with luminescese in of Cu(II) in aq. solution.
A little bit of background.
I am not a chemist, never done chemistry professionally and the last time I had a chemistry class was when I studied Biology some years back.
This is for some self-made presents I want to hand out around Christmas.
I want to make some lamps akin to the self-made Nuka Cola bottles.
While I like the blue glow, quinine is a restricted substance as it is poisonous in larger quantities.
That and the fact that tonic water contains sugar, makes it an unsuitable substance to use.
After having done some reading, I found that copper provides a nice green glow (at least that is what the Balmer-Rydberg equation says), I would like to replicate.
My plan was to suspend copper in water, solidify the water using epoxy and mount a black light over the epoxy substrate leading to a nice ambient green glow.

So I bought some copper wire(not pure copper, I assume some iron to be in there as well, but copper will be the first to go), a cell-phone charger and a black light for testing.
Prepared the charger, stripped the copper wire and hung them, without them touching each other, on the opposite wires of the charger, in slightly salted(NaCL) water.
I get green foam alright (so Cu(II) is being created), but it is not reacting to the black light as expected.
Is the concentration to weak, too much water, is the black light too weak?
I assume I am missing something very fundamental here and I do not know of where to look specifically.
I might find it but most likely I will not as the body of knowledge regarding chemistry, especially phy. chemistry, which I never took to, is vast.
What would be worse would be to find s.th. that works as expected but is dangerous to handle, either by the recipient or me, so safety is paramount.
e.g. mixing vinegar and copper is a big no no.
I tend to try to work out the formula and looking up properties of products(transitional or final) of the compounds involved and only attempt it when I am successful and satisfied with my reading(safe to handle, easy to dispose of, etc.)


So, do you guys happen to have an idea of what I am doing wrong or can point me into a general direction of where I might find a safe solution.
Cheers

[Corribus]

Not really sure what made you think copper ions were fluorescent because of the Rydberg formula...but it isnt the case.

Tonic water is probably still your best bet for something cheap that glows under a black light. Why is the sugar a problem. Can you use sugar free tonic water?

[quizzicalDude]

Hi Corribus,

Thanks for the reply.
Isn't the Rydberg formula used to determin the wavelength of light that is emitted when an electron is moving up and then down the orbital of an atom after being enticed? And according to that formula,unless I have made a mistake, copper should emit green light.

I will look into getting hold of some sugar free tonic water(didn't occure to me).

That being said, how would I go about determining the fluorescence of a chemical compound then, or put differently:
How would you go about it?

[Corribus]

The Rydberg formula is only really relevant to hydrogenic systems, that is, ones in which there is only a single electron. Moreover, just because something fluoresces, this doesn't mean it fluoresces intensely. In point of fact, everything is technically fluorescent to some degree. But very few molecules fluoresce strong enough to see by eye. And even fewer do so in water.

There aren't too many common, water-dispersible substances that will fluorescence strongly under black light to get the Nuka-Cola effect you're looking for (love the idea tho - I'm a huge Fallout fan as well). Antifreeze often contains fluorescein dye that would work, but it's green not blue. Quinine, as you've noted, is readily available in tonic water, and it does fluoresce strongly a nice deep blue. Probably your easiest bet. Even better would be one of a number of blue laser dyes, like perylene or coumarin-1 (or some other in the coumarin family). But they may be harder to find for your typical consumer (I looked on amazon and didn't see any available) and would need a solvent other than water (alcohol, e.g.). If you're giving these as gifts, that could be a problem.

[quizzicalDude]

Hello Corribus,
thanks for the hints and sorry for the late reply. I was quite busy, but followed up on what you said.

Out of curiosity what would I use for a non hydrogenic system, or a system with multiplel electrons as in molecules to calculate the same thing?

I checked out antifreeze.
They have glycol in their antifreeze and it appeared to have no interaction with blacklight (took my torch to the store and shone into the container).
Are there any lipophile substances exhibiting luminescent properties?
I also noticed that although dry tonic contained quinen and was contained in a glass bottle, shining my blacklight at it, did not yield a glowing effect.
I have the suspicion, that I have a UV-torch, but not a blacklight one.
Or are there any other explanations.
Sincerly

dude

[Corribus]

Out of curiosity what would I use for a non hydrogenic system, or a system with multiplel electrons as in molecules to calculate the same thing?

There's no easy formula. It's just something you kind of have to learn, like trivia. Some sophisticated computer programs can make reasonably good predictions. But it's really still a predominantly experimental science.

I checked out antifreeze.
They have glycol in their antifreeze and it appeared to have no interaction with blacklight (took my torch to the store and shone into the container).
Are there any lipophile substances exhibiting luminescent properties?
I also noticed that although dry tonic contained quinen and was contained in a glass bottle, shining my blacklight at it, did not yield a glowing effect.
I have the suspicion, that I have a UV-torch, but not a blacklight one.
Or are there any other explanations.

A few things:
1. Usually, antifreeze = (ethylene) glycol. Fluorescein is often added to glycol-based antifreeze as a tracer to help mechanics find leaks. I don't know if the package usually indicates whether the tracer is added.
2. Packaging materials, particularly plastic ones, frequently have UV-stabilizers and blockers added (to protect the polymer and the packaged contents), so it is possible that the packaged substance could be fluorescent but you won't see it if you illuminate it through the package (even if it looks clear), since the package absorbs all the UV. Not saying that's the case here, but good to keep in mind.
3. You may want to check that the peak wavelength of your black light is a match to the absorption of quinine or fluorescein. For example, fluorescein has absorption maxima at wavelengths <300 nm in ethanol (see here). If your black light has a max output at 370 nm, say, where fluorescein absorbs no light, then you shouldn't expect to see fluorescence (your molecule has to absorb light to emit it). On the other hand, quinine sulfate looks like it absorbs well between 350-400 nm, so a 370 nm black light should excite it quite well. As a side note, if you are looking at spectral data, take note of the solvent, because the wavelengths do shift if the solvent changes. Usually this is more significant for the fluorescence color than the absorption wavelength.

So, basically, you'll want to determine what the light wavelength output of your light is, then make sure it matches the absorption of whatever your fluorescent molecule is.