[Ifeffit] Sealed Sample Cell

Bhoopesh Mishra bhoopeshm at gmail.com
Tue Nov 11 15:01:10 CST 2008

Dear All,
        I am planning to conduct an EXAFS experiment which involves dealing
with methyl mercury. Obviously, I want to be as cautious as I can in sealing
the sample. In that connection, I am wondering if anyone on this forum can
advise me regarding the best way to have a completely sealed (air tight)
sample holder. My requirements are given below. Third requirement is not as
important as the first two.

1. Sample cell (or the front and rear exit) should be made of low scattering
material that would not attenuate photons too much at ~ 10-12 keV.
2. The sample cell should be a perfectly sealed, as gaseous phase methyl
mercury or even di-methyl mercury could be produced in the cell.
3. I would like to inject solution using syringe in the sealed sample holder
(if possible, this requirement is not necessary).

Among several possibilities, I am thinking of designing a cuvette shaped
rectangular box with a thin bottom section, and probably using some sort of
polypropylene such that scattering is as low as possible. It should be easy
to put two silicon rubber septa on the top.

Other possibility could be using a thick Beryllium window (and please
forgive my naivete' here - isn't there some restriction in using Be) on both
the front and back of a rectangular or cylindrical box with rubber stopper
at the top.

The easiest and probably the best would be to have a commercially available
sample cell that can serve my purpose.  I don't know any commercially
available product like that. But I suspect, people who work with volatile
material and/or radioactive material might know a lot about it.

If you know anything, please write me back. Any comments, suggestions, or
criticism would be highly appreciated.

PS: Sealing with kapton tape (or any other thin film) might not be enough in
this case as gaseous phase methyl mercury might diffuse through kapton, and
also air might diffuse through kapton making the inside of the cell
environment aerobic while I need to do this experiment anaerobically.

Thanks for your help!
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