Electron Attachment in Sulfur Hexafluoride Using Monoenergetic Electrons

Abstract

Electron attachment leading to the formation of SF6— and SF5— in sulfur hexafluoride has been investigated using nearly-monoenergetic electrons of established energies of less than 2 ev. The dissociative attachment process leading to the formation of SF5— maximizes at less than 0.1 ev and then decreases to zero at approximately 1.5 ev. In the case of resonance capture leading to the formation of SF6—, the capture process occurs at less than 0.1 ev and only over an energy range estimated to be not larger than 0.05 ev. This leads to an estimated cross section for this resonance capture process of 10—15 cm2. A discussion is given of the method used in the establishment of the electron energy scale at such low energies and the use of the resonance capture process for measuring electron energy distributions.

Flame inhibition with electron attachment as the first step

“…The ratio of SF^"/SF^" was less than 1/20, which is in agreement with Hickam and Fox [21] , and it is tempting to explain the ineffectiveness of SF, as an inhibitor by the fact that too few residual radicals are formed. However, this may not be a valid explanation, since Hickam and Berg [22] found that the ratio of SF,-"/SF^" depends on temperature, being .25 at 80°C and 1.5 at 280^C .…”

New concept of gas purification by electron attachment

“…The estimated result shows that electron energy in the reactor is more than 0.3 eV. Hickam and Fox (1956) have reported the variation in the electron energy of the yield of SF; and SF; by electron impact in SF,, and shown that SF; is the main ion in case that electron energy is more than 0.3 eV. It can thus be seen that the dissociative attachment given by Eq.…”

“…1 and 2 (Hickam and Fox, 1956). Reaction-rate constants of electron attachment depend on electron energy, and electron energy depends on the ratio of electric field strength, E , to pressure, p , or, E/p.…”

“…For example, electron attachment to SF, is given as follows (Hickam and Fox, 1956). SF; is produced by the impact of electrons with nearly zero energy: SF, + e + SF;.…”

Negative ion adsorption by the ion source surface as a factor influencing ion lifetime measurements

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