Université de Fribourg

Two-dimensional spectra of electron collisions with acrylonitrile and methacrylonitrile reveal nuclear dynamics

Regeta, Khrystyna ; Allan, Michael

In: The Journal of Chemical Physics, 2015, vol. 142, no. 18, p. 184307

Detailed experimental information on the motion of a nuclear packet on a complex (resonant) anion potential surface is obtained by measuring 2-dimensional (2D) electron energy loss spectra. The cross section is plotted as a function of incident electron energy, which determines which resonant anion state is populated, i.e., along which normal coordinate the wave packet is launched, and of the...

Université de Fribourg

Electron scattering from krypton: High-resolution experiments and B-spline R-matrix calculations

Zatsarinny, O. ; Bartschat, K. ; Allan, Michael

In: Journal of Physics: Conference Series, 2012, vol. 388, no. 01, p. 012008

In a joint experimental and theoretical effort, we carried out a detailed study of e-Kr collisions. For elastic scattering and excitation of the 4p⁵5s states, we present total and angle-differential cross sections over the entire angular range (0°-180°) for a number of energies, as well as energy scans for selected angles. The experimental results are in very satisfactory agreement with...

Université de Fribourg

Absolute cross sections for electron collisions with diacetylene: elastic scattering, vibrational excitation and dissociative attachment

Allan, Michael ; May, Olivier ; Fedor, Juraj ; Ibǎnescu, Bogdan C ; Andrić, Lidija ; Winstead, Carl ; McKoy, Vincent

In: Journal of Physics: Conference Series, 2012, vol. 388, no. 5, p. 052082

We present absolute experimental cross sections for elastic scattering, vibrational excitation by electron impact and for dissociative electron attachment to 1,3-butadiyne, as well as calculations of the elastic cross sections.

Université de Fribourg

Electron collisions with CO: Elastic and vibrational excitation cross sections

Allan, Michael

In: Physical Review A, 2010, vol. 81, no. 04, p. 042706

Absolute differential elastic and vibrational excitation cross sections up to v=11 were measured for CO in scattering angle ranges extending to 180° at energies between 0.2 and 5 eV (and an elastic measurement at 10 eV). The lowest angles were 0° for inelastic scattering and between 5° and 20° for elastic scattering, depending on energy. Integral cross sections were derived by integrating...

Université de Fribourg

New light on the Kr⁻(4p⁵5s²) Feshbach resonances: high-resolution electron scattering experiments and B-spline R-matrix calculations

Hoffmann, T. H. ; Ruf, M.-W. ; Hotop, Hartmut ; Zatsarinny, O. ; Bartschat, K. ; Allan, Michael

In: Journal of Physics B: Atomic, Molecular and Optical Physics, 2010, vol. 43, no. 8, p. 085206

In a joint experimental and theoretical effort, we carried out a detailed study of electron scattering from Kr atoms in the energy range of the low-lying Kr⁻($4p^5 5s^2$) Feshbach resonances. Absolute angle-differential cross sections for elastic electron scattering were measured over the energy range 9.3–10.3 eV with an energy width of about 13 meV at scattering angles between 10° and...

Université de Fribourg

Absolute angle-differential cross sections for electron-impact excitation of neon within the first 3.5 eV above threshold

Allan, Michael ; Franz, K. ; Hotop, H. ; Zatsarinny, O. ; Bartschat, K.

In: Journal of Physics B: Atomic, Molecular and Optical Physics, 2009, vol. 42, no. 4, p. 044009

Absolute angle-differential cross sections for excitation of neon atoms to the four 2p⁵3s and to selected 2p⁵3p levels have been determined as a function of electron energy up to 3.5 eV above threshold at the scattering angles of 0°, 45°, 90°, 135° and 180°. In addition, the cross sections were recorded as function of scattering angle from 0° to 180° at 18 eV for the 2p⁵3s levels and...

Université de Fribourg

Absolute angle-differential elastic and vibrational excitation cross sections for electron collisions with tetrahydrofuran

Allan, Michael

In: Journal of Physics B: Atomic, Molecular and Optical Physics, 2007, vol. 40, no. 17, p. 3531

Absolute angle-differential elastic and vibrational excitation cross sections for electron collisions with tetrahydrofuran were measured in the energy range 0.1–20 eV, extending existing measurements to lower energies. The elastic cross sections were measured as a function of scattering angle from 10° to 180° at energies of 2 eV, 6 eV, 10 eV and 20 eV, and as a function of electron energy at...

Université de Fribourg

Dissociative electron attachment and electron energy-loss spectra of phenyl azide

Živanov, Svetlana ; Ibanescu, Bogdan C. ; Paech, M. ; Poffet, Martine ; Baettig, Pio ; Sergenton, A.-C. ; Grimme, S. ; Allan, Michael

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,...

Université de Fribourg

Near-threshold absolute angle-differential cross sections for electron-impact excitation of argon and xenon

Allan, Michael ; Zatsarinny, O. ; Bartschat, K.

In: Physical Review A, 2006, vol. 74, p. 030701

Absolute angle-differential cross sections for electron-impact excitation of argon and xenon atoms to the lowest four np⁵(n+1)s levels, and the 5p⁵5d[7/2]₃ level in xenon, have been measured and calculated as a function of electron energy up to a few eV above threshold at a fixed scattering angle of 135°. For argon, very good agreement is observed...

Université de Fribourg

Low-energy electron attachment to SF₆ molecules: Vibrational structure in the cross-section for SF₆⁻ formation up to 1 eV

Braun, M. ; Ruf, M.-W. ; Hotop, Hartmut ; Allan, Michael

In: Chemical Physics Letters, 2006, vol. 419, p. 517–522

In high resolution electron attachment to SF₆, cusp structure due to interchannel coupling has been observed in the cross-section for SF₅⁻ formation at the thresholds for vibrational excitation of the SF₆(v₁) mode up to v₁ = 10. It is superimposed on the broad band peaking around 0.55 eV which has been previously attributed to attachment into a repulsive potential...