Probably not really sputter coated, but more likely vacuum evaporated at low vacuum. Goldstein et al states that "For a variety of reasons (Echlin et al., 1985), it is not possible to sputter carbon by either diode or plasma-magnetron laboratory coaters." These coaters basically generate a plasma from the gas in the chamber using high DC voltage. Ion-beam sputtering could work with a carbon target but that seems less likely as that sort of apparatus is not so common, and low vacuum evaporation would basically do the same thing where there is enough gas in the chamber to scatter carbon to coat reasonably in three dimensions. For flat/polished specimens, I can't imagine why you would use any sort of sputtering technique which has all kinds of contamination and thickness variation problems. We have a (now obsolete) xenon magnetron coater that attempts to deal with this for metal coating by sputtering Ti using Xe as a sputtering gas behind a shield first to get rid of most of the free remaining oxygen, etc. at low vacuum, then introduces more Xe gas so the procedure is very clean when you get to sputtering the second coating target (Pt in our case for SEM) after removing the shield. Yes, Xe and Pt, now those are some cheap consumables there for sure...

-- John J. Donovan [log in to unmask] University of Oregon (541) 346-4632 (office) 1443 E. 13th Ave (541) 346-4655 (probe) Eugene, OR (541) 346-6854 (FAX) 97403-1241 CAMCOR Web: http://camcor.uoregon.edu/ Facility Web: http://epmalab.uoregon.edu/ Cameca SX100 Schedule: http://camcor.uoregon.edu/wp/calendar/sx100 FEI Quanta Schedule: http://camcor.uoregon.edu/wp/calendar/sem

-- Michael J. Jercinovic Associate Professor Department of Geosciences University of Massachusetts 627 North Pleasant Street Amherst, MA 01003-9297 E-Mail: [log in to unmask] Phone: (413) 545-2431 FAX: (413) 545-1200 http://www.geo.umass.edu/faculty/jercinovic/ Electron Microprobe Laboratory http://www.geo.umass.edu/probe

Moderator: Anette von der Handt, [log in to unmask], Electron Microprobe Lab, University of Minnesota