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sbreheny
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Fluorine in quartz?
Hi all,
There is a seller from the Netherlands on eBay who claims to be selling quartz ampoules containing a mixture of 67% He and 33% F:
http://www.ebay.com/itm/141404701586
Of course, fluorine is notoriously difficult to store in any kind of transparent container. Is it true that a diluted mixture with Helium like this
will not attack quartz?
My Google research so far indicates that mixtures like this are used in excimer lasers, but I couldn't find details about the envelope which contains
such a mixture inside an excimer laser and whether it is quartz.
Sean
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Amos
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As far as I've been told, fluorine attacks and combusts SiO2...
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UnintentionalChaos
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Low pressure F2 mixed with He in what is probably annealed quartz has a reasonable lifetime as an element sample. How long exactly, I don't
know, but it's prevalent enough that I've heard of it before.
Department of Redundancy Department - Now with paperwork!
'In organic synthesis, we call decomposition products "crap", however this is not a IUPAC approved nomenclature.' -Nicodem
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elementcollector1
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There are ways to even further extend the lifespan of the ampoule, but yes, this person is most likely legitimate.
Elements Collected:52/87
Latest Acquired: Cl
Next in Line: Nd
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sbreheny
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Thanks for your reply. I don't think it combusts (maybe finely divided SiO2 would) but rather I think it etches it, until the F2 has all reacted or
the SiO2 is etched all the way through and the remaining F2 leaks out.
However, that's what happens with full-strength F2. Maybe if diluted sufficiently with an inert gas, the rate of reaction with the SiO2 is drastically
reduced?
I am in the process of making two full (as full as possible) periodic table element sets and I purchased two of these ampoules. I am looking for
information about whether this is plausible or likely a scam. I have not received the ampoules yet. Anyone think of any way to test whether there is
F2 inside?
The only way I can think to do it would be to put the ampoule inside a larger vessel, along with something that F2 reacts very vigorously with (but
other gasses do not so violently react with - like maybe lithium metal or even iron filings), and break the ampoule inside the larger vessel and watch
for the reaction. Of course, this would have to be done in a good hood for safety in case the outer vessel broke or leaked. There should be enough
metal inside to completely react with the F2 and sequester it. This is, unfortunately, an expensive and destructive test, though.
Sean
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Dan Vizine
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If the F2 is free of trace HF, then quartz can have a lifetime of years before becoming cloudy, especially if the F2 is diluted. Over time, the F2
will abstract hydrogen from the inevitable residual Si-OH species and make the HF. The best samples have ampoules that have had the Si-OHs end-capped.
Absorption spectroscopy could confirm it non-destructively. It simply shines light through the sample and looks for what's missing when it comes out.
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Pok
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@sbreheny: if you only have amateur equipment your idea of destroying the ampoule is probably the only way to check for fluorine. I bet that you will
not detect any fluorine. I don't believe in these "fluorine helium ampoules". If you want to detect it, it is not very logical to take something which
will produce a "violent" reaction. You have to find something that will only produce a positive reaction with fluorine, somethin specific. Lithium is
the exact opposite of that.
Quartz is not a suitable container for elemental fluorine. A tiny amount (some molecules) of water will act as a catalyst an destroy your fluorine
after a while. The only transparent material to store fluorine for centuries are fluorides, e.g. CaF2.
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j_sum1
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Theo Gray has a good description of what you need to do to get a long lasting F2 sample in quartz. It's an easy search. Nothing on He dilution and
I am dubious.
I am surprised that no one seems to be attempting displays of F2 in PTFE. It seems an obvious choice.
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MrHomeScientist
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I feel obliged to link to Theodore Grey's periodic table webpage entry on fluorine, where he describes actual pure fluorine in quartz and the
difficulty in preparing such a container:
http://theodoregray.com/periodictable/Elements/009/index.s7....
Scroll down to "Real visible fluorine." I'll also quote it here for posterity.
| Quote: | Now, respectfully, I must take up a little bit of a qualm with your claim in fluorine...You mention that "There is no transparent container that will
hold it." Granted that is true if you're talking a "forever" time scale, but I strongly believe on a "realistic" scale (a few decades) it can be
done...albeit with some difficulty and great time placed into it. The way best to do it is first to get yourself a pure, single-crystal quartz
tube...Now that means one with an extremely high amount of surface Si-O-Si bonds and VERY few Si-OH endcaps. The best way to do this is to take the
inside portion of the quartz tube and silylate it. Then anneal it at the highest possible temperature that your annealing oven can stand...This will
drive off essentially ALLLLLLL the Si-OH end caps. Because remember, the real killer in fluorine gas for Si-O's is not the fluorine, but the OH's and
their ability to start a chain reaction with small amounts of HF in the fluorine gas. So, the first thing you need to do is get rid of the Si-OH's
which that should take care of as best as possible. Now, being absolutely certain that your quartz tube is flamed and ultra-dry, there's another
step...There was a fluorocarbon grease that DuPont made many years ago that was ultra-high-purity completely fluorinated, medium-high mol.weight
fluorocarbon grease (like a lower-molecular weight Teflon)...Take that stuff and literally melt it into the tube...It's clear and translucent and
won't affect the optics after the next step...So then take a high temperature vacuum oven and turn the tube upside down and melt the grease back
out...What this does is leave a verrrrry thin, essentially invisible layer of fluorocarbon grease layer on the inside of the tube. This layer acts as
a secondary "buffer" layer to the quartz. So IF there are any Si-OH's left on your quartz, they are difficult to get at by the fluorine gas because
the fluorine gas has a difficult time penetrating the grease...This step will add years to your fluorine gas display. Then the more difficult thing to
do is to make sure the quartz tube has a high-purity Teflon screw-top stopper to it so that it can seal ultra-tightly. (again, pure fluorine gas
without any water/HF in it may "trade" fluorines with Teflon, but you still have Teflon; same goes for the grease, the grease may "trade" fluorines as
we've seen in some isotopic studies, but it remains a carbon-fluorine bond).
Then you should get a sacrificial vacuum line (kind of expensive, but it'll just be fogged up after you're done though it's best to throw it away
because the integrity will be damaged) and run your fluorine gas THROUGH A LIQUID NITROGEN FILLED TRAP into your evacuated quartz tube. This is the
most important AND DANGEROUS step. This step is the most important because ALLLLL commercial fluorine sources have either water or HF in them. The
water and HF are what will start the "chain reaction" of eating away at things. And all it takes are a few atoms of these to get it started...But the
N2(l) will definitely remove ALL of them...But the fluorine gas will still have a small amount of volatility to it so as to fill your quartz tube with
approximately a quarter-atmosphere of pure F2. Now if you do anything with fluorine and leave ANY HF or H2O in it, fuggetaboutit...You'll get your
stuff eaten away promptly. You won't get a full atmosphere of fluorine in your quartz sample tube like I said, but it will be enough to see under the
right light and circumstances. And 50 years from now those one or two atoms of HF and H2O that are left in there will eventually have done enough
damage to destroy your sample tube, but I don't plan on worrying about it 50 years from now.
Sorry if that bored you...But I do say it with utmost respect...I spent 10 years fiddling and trying to perfect the best way to get a fluorine sample,
and that's the best way I could get it...So, methinks there are ways to store fluorine safely in a visible specimen tube; it just takes a great amount
of patience, diligence, safety-thoughts and equipment.
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Dan Vizine
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Fluorine eats PTFE, it's only happy when all the carbon is CF4.
The ampoules that I last saw that were prepared in the Ted Grey way were $600 each.
[Edited on 23-10-2014 by Dan Vizine]
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DrMario
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This is how you can store fluorine gas in a container, and still look at it:
put it in a nickel tube which is capped by a CaF2 window (like these) on each side.
Of course, the gas is introduced through the nickel tube wall, which is then sealed shut.
By the way, I don't understand why would anybody want to possess such an ampoule. 30% fluorine gas? What for?
[Edited on 23-10-2014 by DrMario]
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blogfast25
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He's a great guy but not much of an authority on anything.
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HgDinis25
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Quote: Originally posted by DrMario  | This is how you can store fluorine gas in a container, and still look at it:
put it in a nickel tube which is capped by a CaF2 window (like these) on each side.
Of course, the gas is introduced through the nickel tube wall, which is then sealed shut.
By the way, I don't understand why would anybody want to possess such an ampoule. 30% fluorine gas? What for?
[Edited on 23-10-2014 by DrMario] |
Having an ampoule of 30% Fluorine is a mean in itself. It's for the element collector as a Kilo of cocaine is for the drug addict 
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Dan Vizine
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| Quote: Originally posted by DrMario |
By the way, I don't understand why would anybody want to possess such an ampoule. 30% fluorine gas? What for?
[Edited on 23-10-2014 by DrMario] |
Really? You've never run across an element collector?
I've got one. Makes me feel complete....
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DrMario
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I can completely see the point of 1 Kg of cocaine for the druggie. I've never tried it, but I hear cocaine is lots of fun, when consumed.
Fluorine, on the other hand, is probably not much fun when consumed 
No comments on my method? It should be able to store 100% fluorine gas, indefinitely, making said "element collector" very happy. And yet, no signs of
happiness anywhere.
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HgDinis25
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| Quote: Originally posted by DrMario | I can completely see the point of 1 Kg of cocaine for the druggie. I've never tried it, but I hear cocaine is lots of fun, when consumed.
Fluorine, on the other hand, is probably not much fun when consumed
No comments on my method? It should be able to store 100% fluorine gas, indefinitely, making said "element collector" very happy. And yet, no signs of
happiness anywhere. |
hahahaha
Usually the biggest problem is actualy getting the Fluorine...
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DrMario
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| Quote: Originally posted by sbreheny | Hi all,
There is a seller from the Netherlands on eBay who claims to be selling quartz ampoules containing a mixture of 67% He and 33% F:
http://www.ebay.com/itm/141404701586
Of course, fluorine is notoriously difficult to store in any kind of transparent container. Is it true that a diluted mixture with Helium like this
will not attack quartz?
My Google research so far indicates that mixtures like this are used in excimer lasers, but I couldn't find details about the envelope which contains
such a mixture inside an excimer laser and whether it is quartz.
Sean
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Here are a few random comments: the seller doesn't even mention the amount of fluorine/the volume of the ampoule/the partial pressures of the gases.
You would think he/she could be arsed to put that in the eBay description, for a whopping $90!
How 'bout this: I'll seal an ampoule and tell you it contains 33% fluorine, for the low price of $40.
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HgDinis25
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| Quote: Originally posted by DrMario | | Quote: Originally posted by sbreheny | Hi all,
There is a seller from the Netherlands on eBay who claims to be selling quartz ampoules containing a mixture of 67% He and 33% F:
http://www.ebay.com/itm/141404701586
Of course, fluorine is notoriously difficult to store in any kind of transparent container. Is it true that a diluted mixture with Helium like this
will not attack quartz?
My Google research so far indicates that mixtures like this are used in excimer lasers, but I couldn't find details about the envelope which contains
such a mixture inside an excimer laser and whether it is quartz.
Sean
|
Here are a few random comments: the seller doesn't even mention the amount of fluorine/the volume of the ampoule/the partial pressures of the gases.
You would think he/she could be arsed to put that in the eBay description, for a whopping $90!
How 'bout this: I'll seal an ampoule and tell you it contains 33% fluorine, for the low price of $40. |
Then some mad chemist is going to take some refraction index measurments using top of the line, 10 digits past the coma, equipment. All to confirm
some air is present. At least the quartz ampoule is usefull...
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Dan Vizine
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Actually, I've talked with the sellers, Stefan and Chantal ( I think), anyway they were interested in buying F2 from me when I was entertaining the
thought of building a F2 generator. So, for what it's worth, I believe that they are probably legit.
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DrMario
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Not for long, if it's filled with fluorine gas 
BTW, to determine fluorine gas, you only need a UV absorption spectrometer. Not too exotic, unless the money was all spent on building the element
collection. And we all know how bitchin' expensive that astatine is...
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HgDinis25
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| Quote: Originally posted by DrMario |
Not for long, if it's filled with fluorine gas
BTW, to determine fluorine gas, you only need a UV absorption spectrometer. Not too exotic, unless the money was all spent on building the element
collection. And we all know how bitchin' expensive that astatine is... |
There's no problem, I got my astatine for free when buying more than 10 grams of Darmstadtium...
Ontopic: Another way to have Fluorine is to buy a mineral (I've forgotten the name/I'll try to find it later) that has elemental Fluorine gas
inprisioned inside the crystal structure. They discovered it because the miners we're always complaining abou a strange smell whenever they broke a
pice of the mineral.
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DrMario
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| Quote: Originally posted by HgDinis25 |
Ontopic: Another way to have Fluorine is to buy a mineral (I've forgotten the name/I'll try to find it later) that has elemental Fluorine gas
inprisioned inside the crystal structure. They discovered it because the miners we're always complaining abou a strange smell whenever they broke a
pice of the mineral. |
That would be fluorite, CaF2 (which, BTW, I mentioned earlier).
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UnintentionalChaos
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| Quote: Originally posted by HgDinis25 | | Quote: Originally posted by DrMario |
Not for long, if it's filled with fluorine gas
BTW, to determine fluorine gas, you only need a UV absorption spectrometer. Not too exotic, unless the money was all spent on building the element
collection. And we all know how bitchin' expensive that astatine is... |
There's no problem, I got my astatine for free when buying more than 10 grams of Darmstadtium...
Ontopic: Another way to have Fluorine is to buy a mineral (I've forgotten the name/I'll try to find it later) that has elemental Fluorine gas
inprisioned inside the crystal structure. They discovered it because the miners we're always complaining abou a strange smell whenever they broke a
pice of the mineral. |
It's called fetid fluorite or Antozonite. Irradiation of the calcium fluoride by decaying uranium causes small inclusions of fluorine gas to form.
Department of Redundancy Department - Now with paperwork!
'In organic synthesis, we call decomposition products "crap", however this is not a IUPAC approved nomenclature.' -Nicodem
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Dan Vizine
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| Quote: Originally posted by DrMario | I can completely see the point of 1 Kg of cocaine for the druggie. I've never tried it, but I hear cocaine is lots of fun, when consumed.
Fluorine, on the other hand, is probably not much fun when consumed
No comments on my method? It should be able to store 100% fluorine gas, indefinitely, making said "element collector" very happy. And yet, no signs of
happiness anywhere. |
I do have a comment. It won't work because you have no way to make gas tight seals between the salt and the metal tube that won't be attacked by the
halogen.
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Arcuritech
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| Quote: Originally posted by Dan Vizine |
...It won't work because you have no way to make gas tight seals between the salt and the metal tube that won't be attacked by the halogen.
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What about an o-ring made of teflon or another fluorinated polymer?
Even the idea of creating a direct bond between the Ni and the CaF2 isn't so inconceivable because the nickel withstands attack by
F2 by the formation of a NiF2 passivation coating on contact. That layer could be affixed to the the CaF2 using a
lower melting fluoride salt as a "solder".
*edited to remove typo*
[Edited on 2014-10-24 by Arcuritech]
"If we knew what we were doing, it wouldn't be called research." -Albert Einstein
"There are few things -- whether in the outward world, or, to a certain depth, in the invisible sphere of thought -- few things hidden from the man
who devotes himself earnestly and unreservedly to the solution of a mystery." -Nathaniel Hawthorne ("Roger Chillingworth")
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