Electron attachment to CF{sub 3} and CF{sub 3}Br at temperatures up to 890 K: Experimental test of the kinetic modeling approach
- Air Force Research Laboratory, Space Vehicles Directorate, Kirtland Air Force Base, New Mexico 87117 (United States)
- Institut fur Physikalische Chemie, Universitaet Goettingen, Goettingen (Germany)
Thermal rate constants and product branching fractions for electron attachment to CF{sub 3}Br and the CF{sub 3} radical have been measured over the temperature range 300-890 K, the upper limit being restricted by thermal decomposition of CF{sub 3}Br. Both measurements were made in Flowing Afterglow Langmuir Probe apparatuses; the CF{sub 3}Br measurement was made using standard techniques, and the CF{sub 3} measurement using the Variable Electron and Neutral Density Attachment Mass Spectrometry technique. Attachment to CF{sub 3}Br proceeds exclusively by the dissociative channel yielding Br{sup -}, with a rate constant increasing from 1.1 Multiplication-Sign 10{sup -8} cm{sup 3} s{sup -1} at 300 K to 5.3 Multiplication-Sign 10{sup -8} cm{sup 3} s{sup -1} at 890 K, somewhat lower than previous data at temperatures up to 777 K. CF{sub 3} attachment proceeds through competition between associative attachment yielding CF{sub 3}{sup -} and dissociative attachment yielding F{sup -}. Prior data up to 600 K showed the rate constant monotonically increasing, with the partial rate constant of the dissociative channel following Arrhenius behavior; however, extrapolation of the data using a recently proposed kinetic modeling approach predicted the rate constant to turn over at higher temperatures, despite being only {approx}5% of the collision rate. The current data agree well with the previous kinetic modeling extrapolation, providing a demonstration of the predictive capabilities of the approach.
- OSTI ID:
- 22118542
- Journal Information:
- Journal of Chemical Physics, Vol. 138, Issue 20; Other Information: (c) 2013 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA); ISSN 0021-9606
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
74 ATOMIC AND MOLECULAR PHYSICS
70 PLASMA PHYSICS AND FUSION TECHNOLOGY
AFTERGLOW
BRANCHING RATIO
BROMINATED ALIPHATIC HYDROCARBONS
CARBON COMPOUNDS
DISSOCIATION
ELECTRON ATTACHMENT
ELECTRON-MOLECULE COLLISIONS
ELECTRONS
EXTRAPOLATION
FLUORINATED ALIPHATIC HYDROCARBONS
LANGMUIR PROBE
MASS SPECTROSCOPY
PYROLYSIS
RADICALS
REACTION KINETICS
SIMULATION
STANDARDS
TEMPERATURE RANGE 0400-1000 K