promethium longevity...

[zixxer]

Okay.. I collect watches.. primarily Seiko auto's, which use promethium-147 (iirc) as the luminous material on the hands and indices. This stuff will glow brightly for about 10 min after coming inside, and then will stay luminous for about 10 hours (throughout the night..)

Does promethium 'degenerate'.. as in.. if you put it in front of a blacklight to make it glow BRIGHT, does this reduce the longevity?

 

[Shalmanese]

From: http://www.scescape.net/~woods/elements/promethium.html

"Promethium salts luminance in the dark with a pale blue or greenish glow, due to their high radioactivity." Radioactivity is unaffected by any chemical process. So unless you are firing slow neutrons at it, it should glow the same regardless of what you do to it. Incidentally, PM147 has a half life of 2.7 years so a 3 year old watch should glow half as bright as a new one. Can you buy replacement hands for it because otherwise it would only have around a 5 year servicable lifespan.

 

[Mark R]

The Pm won't be affected, but the phosphor (which actually produces the light) might be. However, it's unlikely to be of much significance - I would expect the phosphor to last several thousand hours in front of the UV.

Promethium-147 is available at a cost of about 50c/Ci.

Hehe. Anyone know if eBay allow the trading of radioactive materials?

 

[Shalmanese]

Whats a Ci?

 

[Mark R]

1 Ci = 37 GBq

1 Bq = 1 disintegration/s

1 Ci is more than I'd want sitting around on my desk

 

[PrinceXizor]

Since you have to have an NRC license to deal in sealed source Amercium 241 (Ionization smoke detectors) which have so little radiation its safe to eat them (no, I haven't tested this theory)...I'd say eBay doesn't sell this....though I'm sure that wouldn't stop someone from trying...

P-X

 

[Shalmanese]

Ci = Curie?