Refine my results

Specific Collection

Language

Université de Fribourg

Double 1s shell ionization of Si induced in collisions with 1–3-MeV protons

Kavčič, Matjaz ; Tökési, K.

In: Physical Review A, 2005, vol. 72, p. 062704

The double 1s ionization of Si induced in collisions with protons was studied by measuring the K x-ray emission of a solid Si target ionized by the impact of 1–3-MeV protons. In order to resolve the hypersatellite contributions corresponding to the radiative decay of the double 1s vacancy state, a high-resolution crystal spectrometer was employed yielding sub-eV energy...

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...

Université de Fribourg

Absolute angle-differential cross sections for electron-impact excitation of neon atoms from threshold to 19.5 eV

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

In: Journal of Physics B: Atomic, Molecular and Optical Physics, 2006, vol. 39, p. L139-L144

Absolute angle-differential cross sections for electron-impact excitation of neon atoms to the four levels with the (2p⁵3s) configuration have been determined both experimentally and theoretically for incident energies from threshold up to 19.5 eV at scattering angles of 135° and 180°. Excellent agreement between the experimental data and theoretical predictions, obtained by a Breit–Pauli...

Université de Fribourg

Multiple-scattering suppression in dynamic light scattering based on a digital camera detection scheme

Zakharov, Pavel ; Bhat, Suresh Kumar ; Schurtenberger, Peter ; Scheffold, Frank

In: Applied Optics, 2006, vol. 45, no. 8, p. 1756-1764

We introduce a charge-coupled device (CCD) camera-based detection scheme in dynamic light scattering that provides information on the single-scattered autocorrelation function even for fairly turbid samples. It is based on the single focused laser beam geometry combined with the selective cross-correlation analysis of the scattered light intensity. Using a CCD camera as a multispeckle...

Université de Fribourg

Resonant X-ray Raman scattering for Al, Si and their oxides

Szlachetko, Jakub ; Berset, Michel ; Dousse, Jean-Claude ; Fennane, Karima ; Szlachetko, Monika ; Barrett, R. ; Hoszowska, Joanna ; Kubala-Kukus, A. ; Pajek, M.

In: Nuclear Instruments and Methods in Physics Research B: Beam Interactions with Materials and Atoms, 2005, vol. 238, p. 353

High-resolution measurements of the resonant X-ray Raman scattering (RRS) of Al and Si and their oxides were performed at the European Synchrotron Radiation Facility (ESRF) in Grenoble, France, using a von Hamos Bragg-type curved crystal spectrometer. To probe the influence of chemical effects on the RRS X-ray spectra, Al₂O₃ and SiO₂ samples were also investigated. The X-ray RRS spectra...

Université de Fribourg

Elastic scattering, vibrational excitation, and attachment in low-energy electron-SF₆ scattering: Experiment and effective range theory

Fabrikant, Ilya I. ; Hotop, Hartmut ; Allan, Michael

In: Physical Review A, 2005, vol. 71, p. 022712-22721

Cross sections at low energies for vibrationally elastic and inelastic scattering, as well as electron attachment to SF₆, have been calculated using a multichannel effective range theory (ERT) with complex boundary conditions. The most active vibrational modes, the totally symmetric mode ν1 and the infrared active mode ν3, have been included in the calculation. The ERT parameters were fitted...

Université de Fribourg

The assignment of dissociative electron attachment bands in compounds containing hydroxyl and amino groups

Skalický, Tomás ; Allan, Michael

In: Journal of Physics B: Atomic, Molecular and Optical Physics, 2004, vol. 37, p. 4849-4859

Dissociative electron attachment (DEA) spectra were recorded for methanol, phenol, diethylamine, tetramethylhydrazine, piperazine, pyrrole and N,N-dimethylaniline. Comparison with He I photoelectron spectra permitted the assignment of virtually all DEA bands in the saturated compounds to core excited Feshbach resonances with double occupation of Rydberg-like orbitals and various Koopmans' states...

Université de Fribourg

Electron collisions with NO: Elastic scattering, vibrational excitation, and ²Πi1/2 ⇌ ²Π3/2 transitions

Allan, Michael

In: Journal of Physics B: Atomic, Molecular and Optical Physics, 2005, vol. 38, p. 603

Absolute differential elastic and vibrational excitation cross sections have been measured for NO at 135° with resolution of the ²Π1/2 and ²Π3/2 spin-orbit components of the ground electronic term. The electronic fine structure excitation is dominated by the ³Σ⁻ and the ¹Δ resonances of NO⁻, the nonresonant contribution is very small. The cross section is very large, it has about the...

Université de Fribourg

Transitions between the ²Π₁͵₂ and ²Π₁͵₃ spin-orbit components of NO induced by impact of slow electrons

Allan, Michael

In: Physical Review Letters, 2004, vol. 93, p. 063201-63204

The electron impact cross section for the transition between the ²Π₁͵₂ and ²Π₁͵₃ spin-orbit components of the ground electronic term of nitric oxide, separated by 15 meV, has been measured as a function of electron energy at a scattering angle of Θ= 135°. It is dominated by the ³Σ⁻ and the ¹Δ resonances. Its magnitude is very large, at peak about equal to that of the elastic...

Université de Fribourg

Exchange constants and spin dynamics in Mn₁₂-acetate

Honecker, A. ; Fukushima, N. ; Normand, Bruce ; Chaboussant, G. ; Güdel, Hans-Ulrich

In: Journal of Magnetism and Magnetic Materials, 2005, vol. 290-291, p. 966-969

We have obtained new inelastic neutron scattering (INS) data for the molecular magnet Mn₁₂-acetate which exhibit at least six magnetic peaks in the energy range 5–35 meV. These are compared with a microscopic Heisenberg model for the 12 quantum spins localised on the Mn ions, coupled by four inequivalent magnetic exchange constants. A fit to the magnetic susceptibility under the constraint...