A mass spectrometric study of the neutral and positive ionic species involved in carbon deposition from r.f. discharges in carbon containing gases

✍ Scribed by H.E. Evans; P.P. Jennings

• Publisher: Elsevier Science
• Year: 1968
• Tongue: English
• Weight: 1011 KB
• Volume: 6
• Category: Article
• ISSN: 0008-6223
• DOI: 10.1016/0008-6223(68)90014-6

✦ Synopsis

A mass spectrometric study of species present in radio frequency discharges in binary mixtures of carbon dioxide, carbon monoxide, methane, oxygen and helium has been made. The positive ion spectra have been correlated with observations of deposit formation. Rates of formation and oxidation of deposits have been measured gravimetrically.

Deposits were formed from all carbon monoxide/methane mixtures and from a number of the other mixtures. In the absence of methane the ions C+, C&O+, C&O,+ (and possibly C,+) or their neutral precursors were thought to be involved in deposition. In methane-containing mixtures the ion distribution was dependent on the nature of the reacting gases. We deduced that reactions of the sort:

were important in our system and that deposition from mixtures containing methane and oxygen involved reactions of CH, formed in this way.

The results are interpreted as showing that deposition and corrosion reactions occur simultaneously. Deposition occurs when the rate of the deposition reaction exceeds that of the corrosion reaction.