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Elemental Analysis of Contaminated Nuts

Elemental Analysis of Contaminated Nuts. Jeffrey W. Elam Argonne National Laboratory. Background:. Ossy performed a high-temp vacuum bake of a frit-sealed glass base and sidewall After the bake, there was contamination in the chamber – black deposits.

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Elemental Analysis of Contaminated Nuts

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  1. Elemental Analysis ofContaminated Nuts Jeffrey W. Elam Argonne National Laboratory

  2. Background: • Ossy performed a high-temp vacuum bake of a frit-sealed glass base and sidewall • After the bake, there was contamination in the chamber – black deposits. • Ossy shipped contaminated nuts, along with clean nuts, to ANL for analysis • Jeff did EDAX (energy dispersive analysis of X-rays) in the SEM.

  3. Nuts mounted to SEM stage using carbon tape Contaminated with black residue Clean

  4. SEM images of clean nut: This entire field of view used for EDAX in the following slide

  5. EDAX of clean nut Detail showing nice fit to Ag, Sn region (blue line) indicating we have only the elements indicated

  6. EDAX of clean nut Neglecting the surface carbon contamination (I see this on virtually every sample unless I plasma clean) the clean nut is almost entirely Ag. Makes sense since it’s been silver coated.

  7. SEM images of dirty nut: This patch is covered with white spots – I think this is one of the dark regions in the photo on slide 2 This entire field of view used for EDAX in the following slide

  8. EDAX of dirty nut We see new elements on the dirty nut: Cu, Bi, Sn, Cr, Fe. We don’t see any Pb. The Cr and Fe might come from the steel. To me, the Bi is the most suspicious.

  9. More SEM, EDAX of dirty nut Bi Zoom in SEM so one of the white spots in slide 7 is now the entire field of view Neglecting carbon, the white spots are mostly Bi

  10. Conclusion: the white spots in SEM (which are the black residue observed by eye) are mostly bismuth. Is there bismuth in the frit?

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