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Université de Fribourg

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...

Université de Fribourg

Absolute cross sections for dissociative electron attachment to acetylene and diacetylene

May, Olivier ; Fedor, Juraj ; Ibănescu, Bogdan C. ; Allan, Michael

In: Physical Review A, 2008, vol. 77, no. 4, p. 040701

Absolute cross sections for the production of the two astronomy-relevant negative ions H−C≡C⁻ and H−C≡C−C≡C⁻ by dissociative electron attachment to acetylene C₂H₂ and diacetylene C₄H₂ were measured (with a ±25% error bar). Acetylene yielded the C₂H⁻ ion at an electron energy of 2.95 eV with a cross section of 3.6±0.9 pm² and also the C₂⁻ ion at 8.1 eV...

Université de Fribourg

On the role of the II(1/2g) state in spontaneous dissociation of krypton and xenon dimer ions

Fedor, Juraj ; Echt, O. ; Głuch, K. ; Matt-Leubner, S. ; Scheier, P. ; Märk, T.D.

In: Chemical Physics Letters, 2007, vol. 437, no. 4-6, p. 183-188

We have measured kinetic-energy-release distributions (KERD) for spontaneous dissociation of electronically excited dimer ions of krypton and xenon, formed by electron impact ionization of neutral precursors. The data cannot be reconciled by decay of the strongly bound II(1/2u) state that successfully explains dissociation of and Ne₂⁺ and Ar₂⁺. Instead, the KERD is dominated by...

Université de Fribourg

Dissociative electron attachment to HBr: A temperature effect

Fedor, Juraj ; Cingel, M. ; Skalný, J. D. ; Scheier, P. ; Märk, T. D. ; Čížek, M. ; Kolorenč, P. ; Horáček, J.

In: Physical Review A, 2007, vol. 75, p. 022703

The effects of rovibrational temperature on dissociative electron attachment to hydrogen bromide has been investigated from the experimental and theoretical point of view. Theoretical calculations based on the nonlocal resonance model predict a strong temperature effect on the Br⁻ fragment ion yield due to population of higher vibrational and rotational states. A crossed beam experimental setup...