In: AIP Conference Proceedings, 2007, vol. 901, p. 107-116
Methods to measure absolute differential elastic and vibrational excitation cross sections using an electron spectrometer with a magnetic angle changer are discussed. Emphasized are the need to by-pass drifts and to properly correct for the instrumental response function when angle of detection or electron energy are varied. The results are illustrated with cross sections in nitrogen, methane and...
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In: Journal of Physics B: Atomic, Molecular and Optical Physics, 2002, vol. 35, no. 17, p. L387-L395
Structures of vibrational origin were discovered in vibrationally inelastic electron–CO₂ cross sections in the energy range 0.4–0.9 eV, well below the ² Πu shape resonance. They appear in the excitation of higher vibrational levels, in particular the highest members of the Fermi polyads of the type (n, 2m, 0) with n + m = 2–4. The lowest two...
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In: Physica Scripta, 2004, vol. T110, p. 161-165
Absolute differential cross sections were measured at 135° for the elastic and the vibrationally inelastic electron scattering from threshold to 12 eV, with emphasis on the threshold region. In addition, relative dissociative electron attachment spectra were measured from 0.1 to 3.5 eV. Structures of vibrational origin were observed at energies below 1 eV, well below the ²Π shape resonance, in...
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In: Journal of Physics B: Atomic, Molecular and Optical Physics, 2003, vol. 36, no. 16, p. 3397-3409
Absolute differential cross sections were measured at 135° for the elastic and the vibrationally inelastic electron scattering from threshold to 12 eV, with emphasis on the threshold region. In addition, relative dissociative electron attachment spectra were measured from 0.1 to 3.5 eV. Structures of vibrational origin were observed at energies below 1 eV, well below the ²Π shape resonance, in...
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In: Journal of Physics B: Atomic, Molecular and Optical Physics, 2005, vol. 38, no. 20, p. 3655–3672
Absolute differential elastic and vibrational excitation cross sections have been measured for N₂ in the scattering angle ranges starting between 0° and 20° and extending to 180°, at energies between 0.8 and 5 eV. The results agree with many previous measurements, in particular for angles around 90°, but discrepancies were found in some cases for angles close to 0° and 180°. Integral and...
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In: Physical Review Letters, 2001, vol. 87, no. 3, p. 033201
Improvement of resolution of a gas phase hemispherical electron spectrometer (to 7 meV FWHM) permitted separate measurements of the excitation of each member of the well known Fermi dyad in CO₂ by impact of slow electrons. Absolute differential cross sections at a scattering angle of 135° were measured as a function of electron energy. The excitation was found to be highly selective both via...
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In: Journal of Physics B: Atomic, Molecular and Optical Physics, 2003, vol. 36, no. 16, p. 3513-3531
Energy spectra of electrons detached in collisions of Cl⁻ and Br⁻ with atomic hydrogen and deuterium have been measured for laboratory frame ion energies between 0.2 and 8.0 eV. Their shapes agree very well with the predictions of nonlocal resonance theory. Both types of structure predicted by the theory are observed. They are the 'v steps', at ro-vibrational thresholds, and the 'S...
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In: Physical Review Letters, 2002, vol. 89, no. 7, p. 073201
We present experimental and theoretical energy spectra of the electrons detached in collisions of slow Cl⁻ and Br⁻ ions with atomic hydrogen. Nonlocal resonance theory predicts two kinds of features in the spectra: steplike structures associated with rovibrational onsets and steep rises associated with interchannel coupling, the latter being absent in a calculation using the simpler...
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In: Physical Review Letters, 2007, vol. 98, no. 12, p. 123201
Processes induced by the attachment of slow electrons to formic acid and its hydrogen-bonded dimer were studied. The elastic cross section and the cross section for the excitation of low quanta of discrete vibrations were found to be of a similar magnitude for both targets. A dramatic difference was found in the excitation of a vibrational quasicontinuum in the 1–2 eV range with the ejection of...
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In: Journal of Physics B: Atomic, Molecular and Optical Physics, 2007, vol. 40, no. 1, p. 101-109
Electron-induced chemistry—dissociative electron attachment (DEA)—was studied for phenyl azide. The major fragment corresponded to the loss of N₂ and formation of the phenylnitrene anion. This process has an onset already at zero kinetic energy of the incident electron and is interpreted as proceeding via the A″π* electronic ground state of the phenyl azide anion. Other fragments,...
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