Bärbel Fromme
University of Düsseldorf
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Featured researches published by Bärbel Fromme.
Vacuum | 1997
Bärbel Fromme; C. Bethke; M. Möller; Th. Anschütz; E. Kisker
Abstract Electron-exchange processes in excitations within the d-multiplet of the TM-ions in NiO〈100〉 and CoO〈100〉 had been examined by spin-polarized electron energy-loss spectroscopy. The excitations at surface and bulk ions in NiO show a completely different scattering geometry dependence, providing the possibility of distinguishing between both. In addition to the well-known 0.6 eV surface state, the loss-structure at 2.1 eV excitation energy was identified as surface excitation. In CoO, no surface d-d transitions have been found. Different spin-flip intensities in the excitations of the bulk Co-ions had been used to identify multiplicity changing and conserving transitions definitely. By use of the previously found resonance primary energies and suitable scattering geometries, new d-d excitations had been measured in NiO as well as in CoO.
Physics Letters A | 1986
Bärbel Fromme; H Bromme; Dorothee Göckel; Wilhelm Raith
Abstract We report measurements of circularly polarized recombination radiation from a GaAs 0.6 P 0.4 crystal bombarded with longitudinally spin polarized electrons of 10 eV energy. Qualitatively, this process can be considered as the inverse of the photoemission utilized in GaAs and GaAsP polarized-electron sources. The measured degree of circular polarization is 0.29%±0.06% if the crystal is cooled with liquid nitrogen and the incident electrons are 15%±3% polarized.
Journal of Magnetism and Magnetic Materials | 1995
Bärbel Fromme; A. Hylla; C. Kock; E. Kisker; A. Gorschlüter; H. Merz
Electron exchange processes in NiO have been examined by complete spin-polarized electron energy loss spectroscopy. The measurements show a complicated dependence of the spin-flip exchange scattering on incident angle and energy, unexpected from existing theories and measurements on atoms and ferromagnets. The amount of exchange processes is dramatically enhanced in specular scattering geometry for incident energies around 30, 38 and 100 eV, which is attributed to resonant excitation.
Physical Review B | 1994
Bärbel Fromme; M. Schmitt; E. Kisker; A. Gorschlüter; H. Merz
Physical Review Letters | 1996
Bärbel Fromme; M. Möller; Th. Anschütz; C. Bethke; E. Kisker
Physical Review B | 1998
Bärbel Fromme; U. Brunokowski; E. Kisker
Physical Review Letters | 1995
Bärbel Fromme; Ch. Koch; R. Deussen; E. Kisker
Archive | 2000
Bärbel Fromme
Physical Review B | 1989
Bärbel Fromme; Günter Baum; Dorothee Göckel; Wilhelm Raith
Physical Review B | 2001
Bärbel Fromme; V. Bocatius; E. Kisker