No abstract

Absolute cross sections have been measured for reactants typically found in carbon tetrafluoride (CF(4)) discharges for collision energies below a few hundred electron volts. The reactions investigated include collision-induced dissociation and dissociative electron transfer reactions for CF(+)(3) and F(+) colliding with CF(4), and collisional electron detachment for F(-) colliding with CF4. Also presented are measurements of energies and relative intensities of ions generated in dc Townsend CF4 discharges with E/N values ranging from 4 x 10(-18) V m(2) to 25 x 10(-18) V m(2) [4 to 25 kTd]. Ion energy and ion intensity data for the Townsend discharges are analyzed in light of the measured cross sections.

Absolute total cross sections for collisional electron detachment and collision-induced dissociation (CID) have been measured for binary collisions of SF 6-and SF 5-with rare gas and SF 6 targets for laboratory collision energies ranging from about 10 up to 500 eV. The cross sections for electron detachment of SF;; are found to be surprisingly small, especially for the SF 6 target, for relative collision energies below several tens of electron volts. Specifically, detachment onsets are found to occur at around 30 and 90 eV for the rare gas and SF 6 targets, respectively. The CID channel which leads to F-as a product is observed to dominate d~tachment for relative collision energies below 100 eV. The results for the SF s -projectile are remarkably similar to those exhibited for SF;;. The role oflong-lived excited states in the reactant SF 6 ion beam is discussed.