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Collisional electron detachment and decomposition rates of SF/sup /minus///sub 6/, SF/sup /minus///sub 5/, and F/sup /minus// in SF/sub 6/: Implications for ion transport and electrical discharges

Journal Article · · J. Chem. Phys.; (United States)
OSTI ID:5972036

Measured cross sections for prompt collisional detachment and decomposition of SF/sup /minus///sub 6/, SF/sup /minus///sub 5/, and F/sup /minus// in SF/sub 6/ reported in the preceding companion paper are used to calculate detachment coefficients and ion-conversion reaction coefficients as functions of electric field-to-gas density ratio (/ital E///ital N/) for ion drift in SF/sub 6/. Analysis from a model presented here using these coefficients suggests that prompt electron detachment from SF/sup /minus///sub 6/ and SF/sup /minus///sub 5/ in SF/sub 6/ are insignificant processes in such ion-drift experiments. Calculated rates for ion-conversion processes indicate the necessity to: (1) reexamine the previously measured rates in SF/sub 6/ from drift-tube experiments, and (2) use ion kinetic-energy distributions with larger high-energy tails than the standard distributions assumed in earlier calculations. The calculated detachment and reaction coefficients are used in a model which invokes detachment from long-lived energetically unstable states of collisionally excited SF/sup /minus///sub 6/ to explain the pressure dependence of previously measured detachment coefficients and the high detachment thresholds implied by analysis of electrical-breakdown probability data for SF/sub 6/. Consistent with the interpretation of results from earlier work, the model indicates that at high pressure, measured detachment coefficients depend primarily upon rates for ion conversion and prompt collisional detachment from F/sup /minus//.

Research Organization:
National Institute of Standards and Technology, Gaithersburg, Maryland 20899(US); Department of Physics, College of William and Mary, Williamsburg, Virginia 23185
OSTI ID:
5972036
Journal Information:
J. Chem. Phys.; (United States), Journal Name: J. Chem. Phys.; (United States) Vol. 91:4; ISSN JCPSA
Country of Publication:
United States
Language:
English