Inorganic chemistry Cu + AgI or AgSe --> black solid?

We have a small mystery.

In a vacuum chamber with an ion pump, the researchers recently experienced having all the open copper surfaces coate d with a black solid

They had recently introduced AgSe (solid) to the chamber which also contained AgI

One opinion is that the chamber experienc ed an ion discharge which oxidized the copper to copper oxide

Have you-all had this experience before?

Ideas?

Thanks,

-Russ

Russell Vernon, Ph. D.

Director

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University of Californ ia, Riverside

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