Characterization of gaseous species in scanning atmospheric rf plasma with transmission infrared spectroscopy
- Department of Chemical Engineering, Pennsylvania State University, University Park, Pennsylvania 16802 (United States)
A scanning atmospheric radio-frequency (rf) plasma was analyzed with transmission infrared (IR) spectroscopy. The IR analyses were made for the plasmas used for hydrophobic coating deposition and superhydrophobic coating deposition processes. Since the rf plasma was generated in a small open space with a high gas flow rate in ambient air, the density of gas-phase molecules was very high and the plasma-generated reactive species seemed to undergo various reactions in the gas phase. So, the transmission IR spectra of the scanning atmospheric rf plasma were dominated by gas-phase reaction products, rather than plasma-generated intermediate species. In the CH{sub 4}/He plasma used for hydrophobic coating deposition, C{sub 2}H{sub 6}, C{sub 2}H{sub 2}, and a small amount of C{sub 2}H{sub 4} as well as CO were detected in transmission IR. The intensities of these peaks increased as the rf power increased. The CO formation is due to the activation of oxygen and water in the air. In the CF{sub 4}/H{sub 2}/He plasma used for deposition of superhydrophobic coatings, C{sub 2}F{sub 6}, CF{sub 3}H, COF{sub 2}, and HF were mainly detected. When the H{sub 2}/CF{sub 4} ratio was {approx}0.5, the consumption of CF{sub 4} was the highest. As the H{sub 2}/CF{sub 4} ratio increased higher, the C{sub 2}F{sub 6} production was suppressed while the CF{sub 3}H peak grew and the formation of CH{sub 4} were detected. In both CH{sub 4}/He and CF{sub 4}/H{sub 2}/He plasma systems, the undissociated feed gas molecules seem to be highly excited vibrationally and rotationally. The information on plasma-generated reactive species and their reactions was deduced from the distribution of these gas-phase reaction products.
- OSTI ID:
- 21020892
- Journal Information:
- Journal of Vacuum Science and Technology. A, International Journal Devoted to Vacuum, Surfaces, and Films, Vol. 26, Issue 1; Other Information: DOI: 10.1116/1.2823483; (c) 2008 American Vacuum Society; Country of input: International Atomic Energy Agency (IAEA); ISSN 1553-1813
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
ABSORPTION SPECTROSCOPY
CARBON MONOXIDE
CARBON TETRAFLUORIDE
COBALT FLUORIDES
DEPOSITION
DIMETHYL SULFIDE
ETHANE
ETHYLENE
FOURIER TRANSFORMATION
GAS FLOW
HYDROFLUORIC ACID
HYDROGEN
INFRARED SPECTRA
METHANE
OXYGEN
PLASMA
RADIOWAVE RADIATION
TRANSMISSION