Hi John,

I've seen significant variation in thickness using sputter coaters, though using metal targets.  Here is what Ben Buse showed for Ag on a thin section:


https://probesoftware.com/smf/index.php?topic=1232.0


I would assume it's also a problem for carbon sputter coating, though I have not tested a modern carbon sputter coater.

john


On 12/17/2019 10:33 AM, John H Fournelle wrote:
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Does anyone have any comments (direct or indirect evidence) or know of any references, to something I've wondered about for a long time.

Decades ago, someone brought me some samples from materials science here, where I was told that the carbon coating was deposited by sputtering. I had difficulty acquiring good epma results, so I removed the carbon coat, coated in my evaporator, and had good results. From then on, I assumed that 
"sputtering of carbon" might not be as "good" as evaporated carbon, though I never did any true test (yes, the coating thickness might have been greatly different from my standards, I know now).

Was I wrong to cast a negative light upon sputtered carbon coating for epma? Any thoughts?


John Fournelle Ph.D.

Senior Scientist

Department of Geoscience, University of Wisconsin

1215 West Dayton Street, Madison, WI 53706

mobile 608-438-7480

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