Date: Mon, 16 May 2011 14:17:06 -0400
Reply-To: DCHAS-L Discussion List <DCHAS-L**At_Symbol_Here**LIST.UVM.EDU>
Sender: DCHAS-L Discussion List <DCHAS-L**At_Symbol_Here**LIST.UVM.EDU>
From: ILPI <info**At_Symbol_Here**ILPI.COM>
Subject: Re: Inorganic chemistry Cu + AgI or AgSe --> black solid?
In-Reply-To: <BE28425130279043A5B92A2BC7116E233D105E**At_Symbol_Here**>

The copper/silver redox couple favors formation of Cu2+ and Ag(0), no discharge required.  This driving force should be the same whether the source of silver ion is Ag2Se or AgI.

If the AgX solid is being heated or ablated or has some other means of making it into the gas phase, then it could be a direct reaction to Cu2Se, CuSe, Cu2I etc.

As to the identity of the black solid, an SEM-EDAX, if available and possible, should tell you if it has Se or I in it and give you ratios of Cu:X.

Rob Toreki

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On May 16, 2011, at 11:54 AM, Russell Vernon wrote:

We have a small mystery.
In a vacuum chamber with an ion pump, the researchers recently experienced having all the open copper surfaces coated with a black solid
They had recently introduced AgSe (solid) to the chamber which also contained AgI
One opinion is that the chamber experienced an ion discharge which oxidized the copper to copper oxide
Have you-all had this experience before?
Russell Vernon, Ph.D.
Environmental Health & Safety
University of California, Riverside
900 University Ave
Riverside, CA 92521
Direct (951) 827-5119
Admin (951) 827-5528
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