broken tritium vial continues to glow faintly - WTF is going on?

[Helmut.G]

I have received several tritium vials in the last months.

I acidentally broke a yellow vial out of a Nite Glowring on 11-11-2013 by punching through the fragile sealed end of the glass tube with a pointed metal instrument using little strength. This appears to be the weakest part of the glass.

I could hear a weak "pop" sound and, being in a dimly lit room, literally observed the light "going out" as the gas left the vial. Now that I am over the grief of the monetary loss I can say that it was quite an interesting sight.
A split second later I smelled an uncomfortable odour - apparently the manufacturer mixes the tritium with a warning odorant.

I then exhaled, held my breath and opened the window, leaving the room to minimize ingestion of radioactive gas.


Last night I noticed that the supposedly empty vial still glows in the dark.
This glow is really faint. Maybe you have seen glowing wood in a dark forest - this is much weaker.
I will take a photograph later to determine the colour of the glow. Right now the vial is in a completely dark environment.


Has anybody observed something similar?
Does anybody have an explanation?

 

[Helmut.G]

Ok, so I checked and illuminated the vial with a bright flashlight. It certainly has a light phosphorescent afterglow. I will now let it sit in total darkness for a loong time and check if it still glows.

 

[Helmut.G]

Here are some pictures that show the afterglow on some intact tritiums.

Both were shot at the same f/1.8, 1/125 s, ISO 3200.

All vials were illuminated with a high powered photographic flash about 0.1 s before the second picture was taken.

 

[Helmut.G]

well, the thing sat in the dark for several days now - I just opened the box and the glow was just as strong as I remembered. Clearly visible with night adapted vision.

There must be some energy source inside the vial.
Is it somehow possible that a minute amount of tritium gas is mechanically caught inside the phosphor layer? I would expect it to diffuse in a matter of hours, being lighter than helium.
Or has there maybe been a chemical reaction that produced a solid compound containing tritium?
Or else maybe the phosphor contains easily accessible hydrogen atoms that could have been replaced?

 

[Helmut.G]

Wikipedia contains a long list of phosphors http://en.wikipedia.org/wiki/Phosphor - none seem to be organic so the hydrogen atom exchange theory appears to be false.

 

[schizeckinosy]

I have nothing to add but thanks for posting this. It's fascinating!


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[Helmut.G]

Picture time


The broken vial was in complete darkness for at least 70 hours prior to and during the first part of the photo shooting to minimize possible effects of phosphorescent afterglow.

The broken vial was then exposed to a powerful flashlight at a very close distance for some 5 seconds. Additional pictures were taken shortly after this, and then a few minutes later. These pictures confirm the visual observation that the afterglow is very bright only for a fraction of a second and almost completely vanishes in a couple of minutes.


The setup:

A box lined with black cloth, some tritium vials on the left for brightness comparison (green, ice blue, red 3mmx23mm, yellow 3mmx25mm) and a wall between them and the place for the broken vial (yellow 3mmx23mm).
A camera set to expose 1, 4 and 15 seconds (ISO 1600, lens aperture setting f/4.5, actual lens transmission ~f/5.0).
White balance was set to 5000k.




1 second:

the broken vial is hardly visible without software picture manipulation



4 seconds:

all the intact vials are heavily overexposed now (resulting in color shift), broken vial starts to be noticeable



15 seconds:

15 seconds + 1 stop software exposure correction (equivalent to 30 second exposure, but lower image quality):

---

15 seconds, exposing this picture started about 30 seconds after lighting up the broken vial with the flashlight:

30 second equivalent of the above picture:

15 seconds, exposing this picture started about 3 minutes after lighting up the broken vial with the flashlight. you can see that the broken vial is already almost back to "darkness level":

30 second equivalent of the above picture:

So there you have it. The strange glow definitely exists, is very likely not caused by phosphorescence, is very weak and it looks to be the same color as the vial used to be before breaking.

 

[schizeckinosy]

I may be talking out of my rear but I seem to recall that the glass may become radioactive and is activating the phosphorus?


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[inetdog]

Hydrogen (and to almost the same extent the tritium isotope) will penetrate many substances which are not permeable to other gasses. I would not be surprised if some tritium dissolved into the surface layer of the glass.

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[easilyled]

Is it somehow possible that a minute amount of tritium gas is mechanically caught inside the phosphor layer?

My guess is that a small amount of tritium has permanently combined, chemically, with the phosphor layer.
I'm not a chemist so it is only a guess.

 

[CoveAxe]

Hydrogen (and to almost the same extent the tritium isotope) will penetrate many substances which are not permeable to other gasses. I would not be surprised if some tritium dissolved into the surface layer of the glass.

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I'm a research scientist that works with semiconductor fabrication processes, and I think this is likely the correct explanation. Gases will diffuse into materials, especially when left for a long time. This phenomenon is well known and used in CMOS fabrication to grow oxide on silicon. Hydrogen/Tritium is very light and small especially compared to oxygen, and should easily diffuse into glass. If left for long enough (as in, years or more), the gas should diffuse back out. It is also likely that the tritium has bonded with impurities on the inside and surface of the glass, in which case the gas won't diffuse back out. You would need to do some long-term experiments to determine how much of the glow is caused by each.

Here are some published papers that talk about this subject.