Low-energy electron attachment to SF(6). III. From thermal detachment to the electron affinity of SF(6)

2007 | journal article. A publication of Göttingen

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​Low-energy electron attachment to SF(6). III. From thermal detachment to the electron affinity of SF(6)​
Viggiano, A. A.; Miller, T. M.; Friedman, J. F. & Troe, J.​ (2007) 
The Journal of Chemical Physics127(24) art. 244305​.​ DOI: https://doi.org/10.1063/1.2804764 

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Viggiano, Albert A.; Miller, Thomas M.; Friedman, Jeffrey F.; Troe, Juergen
The thermal attachment of electrons to SF(6) is measured in a flowing-afterglow Langmuir-probe apparatus monitoring electron concentrations versus axial position in the flow tube. Temperatures between 300 and 670 K and pressures of the bath gas He in the range of 0.3-9 Torr are employed. Monitoring the concentrations of SF(6)(-) and SF(5)(-), the latter of which does not detach electrons under the applied conditions, an onset of thermal detachment and dissociation of SF(6) at temperatures above about 530 K is observed. Analysis of the mechanism allows one to deduce thermal detachment rate coefficients. Thermal dissociation rate coefficients for the reaction SF(6)(-)-->SF(5)(-)+F can only be estimated by unimolecular rate theory based on the results from Part I and II of this series. Under the applied conditions they are found to be smaller than detachment rate coefficients. Combining thermal attachment and detachment rates in a third-law analysis, employing calculated vibrational frequencies of SF(6) and SF(6)(-), leads to the electron affinity (EA) of SF(6)(-). The new value of EA=1.20(+/- 0.05) eV is significantly higher than previous recommendations which were based on less direct methods. (C) 2007 American Institute of Physics.
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Amer Inst Physics
The Journal of Chemical Physics 



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