Absolute partial and total electron-impact-ionization cross sections for CF sub 4 from threshold up to 500 eV

Electron-impact dissociative ionization of tetrafluoromethane (CF{sub 4}) was studied with the use of a pulsed electron beam time-of-flight apparatus. The absolute partial ionization cross sections of CF{sub 3}{sup +}, CF{sub 2}{sup +}, CF{sub 3}{sup 2+}, CF{sup +}, CF{sub 2}{sup 2+}, F{sup +}, and...

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Bibliographic Details
Published in:Physical review. A, Atomic, molecular, and optical physics Atomic, molecular, and optical physics, 1991-09, Vol.44:5
Main Authors: Ma, C., Bruce, M.R., Bonham, R.A.
Format: Article
Language:English
Subjects:
640304 - Atomic, Molecular & Chemical Physics- Collision Phenomena
ATOMIC AND MOLECULAR PHYSICS
BEAMS
CARBON TETRAFLUORIDE
CHARGED PARTICLES
COLLISIONS
CROSS SECTIONS
DATA
DISSOCIATION
ELECTRON BEAMS
ELECTRON COLLISIONS
ELECTRON-MOLECULE COLLISIONS
ENERGY RANGE
EV RANGE
EV RANGE 10-100
EV RANGE 100-1000
EXPERIMENTAL DATA
FLUIDS
FLUORINATED ALIPHATIC HYDROCARBONS
GASES
HALOGENATED ALIPHATIC HYDROCARBONS
INFORMATION
IONIZATION
IONS
LEPTON BEAMS
MEASURING INSTRUMENTS
MOLECULAR IONS
MOLECULE COLLISIONS
NUMERICAL DATA
ORGANIC COMPOUNDS
ORGANIC FLUORINE COMPOUNDS
ORGANIC HALOGEN COMPOUNDS
PARTICLE BEAMS
SPECTROMETERS
TIME-OF-FLIGHT SPECTROMETERS
TOTAL CROSS SECTIONS
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Summary:Electron-impact dissociative ionization of tetrafluoromethane (CF{sub 4}) was studied with the use of a pulsed electron beam time-of-flight apparatus. The absolute partial ionization cross sections of CF{sub 3}{sup +}, CF{sub 2}{sup +}, CF{sub 3}{sup 2+}, CF{sup +}, CF{sub 2}{sup 2+}, F{sup +}, and C{sup +} were measured from threshold up to 500 eV. The total ionization cross section was obtained by charge weighted summing of all the observed partial ionization cross sections. A total cross section for dissociation into neutral fragments was inferred from our total ionization cross section and the total dissociation cross section of Winters and Inokuti (Phys. Rev. A 25, 1420 (1982)). The present results for the partial ionization cross sections are as much as 9% (CF{sub 3}{sup +}) to 81% (F{sup +}) higher than the previously published absolute measurements of Stephan, Deutsch, and Maerk (J. Chem. Phys. 83, 5712 (1985)) at 80 eV, but are in agreement with their recently revised estimates for the singly charged ions. We also found that dissociative ionization was a dominant process for electron-impact energies above 30 eV, accounting for 85% of the total dissociation cross section at 80 eV.
ISSN:1050-2947
1094-1622
DOI:10.1103/PhysRevA.44.2921