Collisional decomposition of the sulfur hexaflouride anion (SF6-)

Insulating gas mixtures containing SF6 have been promoted to serve as repla cements for pure SF6 in order to reduce SF6 atmospheric emission. It has be en argued that some synergism may be achieved by choosing proper buffer gas es in mixtures with SF6 such that the buffer gases efficiently slow down el ectrons into an energy range where the electron attachment cross section fo r SF6 is large. A complete understanding of the dielectric properties of SF 6 mixtures obviously requires information about electron detachment from SF 6- as collisional electron detachment may be the principal source of discha rge initiation in SF6 mixtures. In this paper, we report total cross-sectio n measurements for electron detachment and collision induced dissociation f or collisions of SF6- with N-2 for collision energies ranging up to a few h undred eV. The experimental results are analyzed using a two-step collision model where the unimolecular decomposition of collisionally excited SF6- i ons is described in a statistical framework. (C) 2001 American Institute of Physics.