>Regarding the use of Ni or stainless steel tubing for fluorination lines.
>We have been moving nanomole quantities of molecular O2 through a vacuum
>line with isotopic fidelity (i.e., no fractionation at the 0.1 to 0.2 per
>mil level) for almost two years. The tubing is 316L stainless steel with
>electropolished interior. Our original system included Ni components. Ni,
>however, reacts readily with O2 and we were able to identify several of
>these components as being sites of isotope fractionation. Indeed in one
>case Ni was visibly tarnished with oxide. Ni-O2 reactions are accelerated
>appreciably at temperatures as low as 35 to 40 C and will proceed even in
>the presence of BrF5. Ni has superior resistance to fluorination, but the
>cost is enhanced susceptibility to O2 attack.
>
>-Ed Young
> Earth Sciences
> University of Oxford

Ed

I was interested in what you say about Ni and 316 stainless steel. I
presume you would not reccomend Ni as a sample holder for laser heating
mineral grains? We use Ni sample trays and although the holes are
repolished after every run I have always been a bit suspicious about their
performance.

Has anyone had experience of using SS316 or materials other than Ni for
sample trays?

Dave Mattey

Geology Department, Royal Holloway College, University of London, Egham
Hill, Egham, Surrey TW20 0EX

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