Faculté des sciences

Absolute cross sections for dissociative electron attachment to HCl, HBr, and their deuterated analogs

Fedor, Juraj ; May, Olivier ; Allan, Michael

In: Physical Review A, 2008, vol. 78, p. 032701

We have measured absolute dissociative electron attachment cross sections for HX and DX (X=Cl and Br) using a trochoidal electron spectrometer equipped with a total ion collection collision chamber, operated both in a field-free passive ion collection mode, and an active ion collection mode, with an extracting electric field. Our results for Br⁻ from HBr are in an excellent... Plus

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    Summary
    We have measured absolute dissociative electron attachment cross sections for HX and DX (X=Cl and Br) using a trochoidal electron spectrometer equipped with a total ion collection collision chamber, operated both in a field-free passive ion collection mode, and an active ion collection mode, with an extracting electric field. Our results for Br⁻ from HBr are in an excellent quantitative agreement with recent predictions of the nonlocal resonance model, but the cross sections for Cl⁻ from HCl and DCl are, respectively, 2.2 times and 2.8 times smaller than the theoretical predictions. Cross sections for the production of H⁻ and D⁻ in the 6–10  eV range are much smaller than those for X⁻ and the isotope effect is much weaker, consistent with the assignment to core-excited Feshbach resonances. There is one exception, however, the 9  eV band in HCl has a large isotope effect.