Attachment coefficients for the reactions of electrons with CCl<sub>4</sub>, CCl<sub>3</sub>F, CCl<sub>2</sub>F<sub>2</sub>, CHCl<sub>3</sub>, Cl<sub>2</sub> and SF<sub>6</sub> determined between 200 and 600 K using the FALP technique
D Smith; N G Adams; E Alge; D Smith; Dept. of Space Res., Univ. of Birmingham, Birmingham, UK; N G Adams; Dept. of Space Res., Univ. of Birmingham, Birmingham, UK; E Alge; Dept. of Space Res., Univ. of Birmingham, Birmingham, UK
Журнал:
Journal of Physics B: Atomic and Molecular Physics
Дата:
1984-02-14
Аннотация:
The rate coefficients, beta , for the attachment reactions of electrons with CCl<sub>4</sub>, CCl<sub>3</sub>F, CCl<sub>2</sub>F<sub>2</sub>, CHCl<sub>3</sub>, Cl<sub>2</sub> and SF<sub>6</sub> have been measured under truly thermal conditions over the approximate temperature range 200-600K using a flowing-afterglow/Langmuir probe apparatus. The beta values obtained at 300K are 3.9*10<sup>-7</sup>, 2.6*10<sup>-7</sup>, 3.2*10<sup>-9</sup>, 4.4*10<sup>-9</sup>, 2.0*10<sup>-9</sup> and 3.1*10<sup>-7</sup> cm<sup>3</sup> s<sup>-1</sup> respectively. From the variation with temperature of beta for the CCl<sub>2</sub>F<sub>2</sub>, CHCl<sub>3</sub> and Cl<sub>2</sub> dissociative attachment reactions, activation energies, E<sub>a</sub>, of 0.15, 0.12 and 0.05 eV respectively were derived. The beta for CCl<sub>4</sub>, CCl<sub>3</sub>F and SF<sub>6</sub> are close to their theoretical limiting values within the temperature range investigated. While Cl<sup>-</sup> was the only product ion observed for the reactions involving chlorine-containing molecules, both SF<sub>6</sub><sup>-</sup> and SF<sub>5</sub><sup>-</sup> were observed for the SF<sub>6</sub> reaction. The data obtained are compared with previous data and the separate influences of electron temperature and gas temperature are noted.
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