Rate coefficients for the attachment reactions of electrons with c-C<sub>7</sub>F<sub>14</sub>, CH<sub>3</sub>Br, CF<sub>3</sub>Br, CH<sub>2</sub>Br<sub>2</sub> and CH<sub>3</sub>I determined between 200 and 600K using the FALP technique
E Alge; N G Adams; D Smith; E Alge; Dept. of Space Res., Univ. of Birmingham, Birmingham, UK; N G Adams; Dept. of Space Res., Univ. of Birmingham, Birmingham, UK; D Smith; Dept. of Space Res., Univ. of Birmingham, Birmingham, UK
Журнал:
Journal of Physics B: Atomic and Molecular Physics
Дата:
1984-09-28
Аннотация:
The rate coefficients, beta , for the attachment reactions of electrons with c-C<sub>7</sub>F<sub>14</sub>, CH<sub>3</sub>Br, CF<sub>3</sub>Br, CH<sub>2</sub>Br<sub>2</sub> and CH<sub>3</sub>I have been determined under truly thermal conditions at temperatures in the range 200-600K using the flowing afterglow/Langmuir probe technique. The beta values (in units of CM<sup>3</sup> s<sup>-1</sup>) at 300K are 6.8*10<sup>-8</sup>, 6*10<sup>-12</sup>, 1.6*10<sup>-8</sup>, 9.3*10<sup>-8</sup> and 1.2*10<sup>-7</sup> respectively. The beta for all of the reactions increase with temperature and approach the theoretical maximum value of beta at high temperatures. From Arrhenius plots, activation energies for the reactions have been determined to be 40, 300, 80, 50 and 25 meV respectively. All of the reactions, except for that with c-C<sub>7</sub>F<sub>14</sub> (for which electron attachment is apparently non-dissociative), proceed by exoergic dissociative attachment producing halogen atomic negative ions. The data are compared with previous data where these are available.
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