TEMPERATURE-DEPENDENCE OF ELECTRON-ATTACHMENT AND DETACHMENT IN SF6 AND C-C4F6

In the temperature, T, range of 300-600 K and the mean electron energy range [is-an-element-of] of 0.19-1.0 eV, the total electron attachmen t rate constant for SF6 and c-C4F6 measured in dilute mixtures with N2 , is virtually independent of T. Under the same experimental condition s the stabilized SF6- anion does not undergo autodetachment but the st abilized c-C4F6- anion undergoes a profound increase in autodetachment (by about four orders of magnitude). This difference between the SF6- and the c-C4F6- anions is attributed to the larger electron affinity of the SF6 molecule compared to the c-C4F6 molecule. The heat-activate d autodetachment for c-C4F6- is related to increases in the internal e nergy content of the C-C4F6- anion and is found to have an activation energy of 0.237 eV. The ''limiting electric field strength'' of SF6 wa s found to increase by approximately 11% as T was increased from 300 t o 600 K.