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

• 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
• ISSN: 1050-2947; 1094-1622
• DOI: 10.1103/PhysRevA.44.2921

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.