Deuterium Oxide and Diamonds

[Simon "M." Jerome <smj1@npl.co.uk>]

In response to several enquiries, the 'no tritium' D2O that I had was 
obtained from the Aldrich Chemical company in 1992. I do not have any 
of the order details, catalogue numbers or indeed any of the material 
left. I had purchased it with the specific purpose of seeing if it 
contained any Tritium, due to the enrichment process. No information on 
the tritium content, or the origin of this material was supplied. The 
measurements made were very simple: a 1 ml aliquot was mixed with 15 ml 
Ecoscint and counted. The count rate obtained was no different from the 
background from local tapwater.

The D2O was supplied in glass ampoules.

I note from the current Aldrich catalogue that they do several versions 
of their 99.9% and 100% D2O in glass ampoules and one (cat no 34,716-7) 
is described as 'low tritium content ~150 dpm/ml). This would have been 
way above our LS background!

So, it still remains a mystery as to why it should have been so 
inactive.

If anyone is interested, I have 2 x 1g 'Poly(ethylene-d4) - presumably 
100% deuterated polythene, ex Merck, Sharp and Dome of Canada and 1 x 
20g 99.7% D2O, ex Norsk Hydro - both the packages look like they came 
from the 50s or 60s, but there is no date on either. Might make 
interesting museum pieces.

On the irradiated gemstones front, coloured diamonds (more valuable 
than the plain type) are sometimes monitored for radioactivity, when it 
is suspected that they have been generated in a neutron flux, rather 
than deep underground. As far as I can recall, the colours come from 
trapped free radicals, rather than a chemical impurity. Also, because 
diamonds tend to be pure carbon, the level of induced activity is very 
low, necessitating taking your counting equipment about 250m below 
ground to resuce the ambient background. Frankly, I can't see what the 
point of worrying about whether the diamond is naturally coloured or 
artificially coloured is, since they are visually indistinguishable and 
not (significantly) radioactive.

The problem comes, as did happen once, when the whole necklace was 
irradiated. The diamonds went a pretty colour, but stayed non active. 
The same could not be said for the gold....it was only when the wearer 
was diagnosed as having radiation burns around the neck that the whole 
story came to light. 

Best wishes,
Simon Jerome
Email:	simon.jerome@npl.co.uk
Web:	http://www.npl.co.uk/