Electron attachment to POCl3: Measurement and theoretical analysis of rate constants and branching ratios as a function of gas pressure and temperature, electron temperature, and electron energy

2006 | journal article. A publication with affiliation to the University of Göttingen.

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​Electron attachment to POCl3: Measurement and theoretical analysis of rate constants and branching ratios as a function of gas pressure and temperature, electron temperature, and electron energy​
van Doren, J. M.; Friedman, J. F.; Miller, T. M.; Viggiano, A. A.; Denifl, S.; Scheier, P. & Mark, T. D. et al.​ (2006) 
The Journal of Chemical Physics124(12) art. 124322​.​ DOI: https://doi.org/10.1063/1.2176613 

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Authors
van Doren, J. M.; Friedman, Jeffrey F.; Miller, Thomas M.; Viggiano, Albert A.; Denifl, S.; Scheier, P.; Mark, T. D.; Troe, Juergen
Abstract
Two experimental techniques, electron swarm and electron beam, have been applied to the problem of electron attachment to POCl3, with results indicating that there is a competition between dissociation of the resonant POCl3- state and collisional stabilization of the parent anion. In the electron beam experiment at zero electron energy, the fragment ion POCl2- is the dominant ion product of attachment (96%), under single-collision conditions. Small amounts (similar to 2% each) of POCl3- and Cl- were observed. POCl3- and POCl2- ion products were observed only at zero electron energy, but higher-energy resonances were recorded for POCl-, Cl-, and Cl-2(-) ion products. In the electron swarm experiment, which was carried out in 0.4-7 Torr of He buffer gas, the parent anion branching ratio increased significantly with pressure and decreased with temperature. The electron attachment rate constant at 297 K was measured to be (2.5 +/- 0.6)x10(-7) cm(3) s(-1), with ion products POCl2- (71%) and POCl3- (29%) in 1 Torr of He gas. The rate constant decreased as the electron temperature was increased above 1500 K. Theory is developed for (a) the unimolecular dissociation of the nascent POCl3- and (b) a stepladder collisional stabilization mechanism using the average energy transferred per collision as a parameter. These ideas were then used to model the experimental data. The modeling showed that D-0(o)(Cl-POCl2-) and EA(POCl3) must be the same within +/- 0.03 eV.
Issue Date
2006
Status
published
Publisher
Amer Inst Physics
Journal
The Journal of Chemical Physics 
ISSN
0021-9606

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