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Dive into the research topics where Bärbel Fromme is active.

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Featured researches published by Bärbel Fromme.


Vacuum | 1997

Electron-exchange processes in bulk and surface d-d excitations in transition-metal oxides

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

Emission of circularly polarized recombination radiation from p-doped GaAsP bombarded with longitudinally polarized electrons

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

Spin-flip low-energy electron-exchange scattering in NiO (100)

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

SPIN-FLIP LOW-ENERGY ELECTRON-EXCHANGE SCATTERING IN NIO(100)

Bärbel Fromme; M. Schmitt; E. Kisker; A. Gorschlüter; H. Merz


Physical Review Letters | 1996

Electron-Exchange Processes in the Excitations of NiO(100) Surface d States.

Bärbel Fromme; M. Möller; Th. Anschütz; C. Bethke; E. Kisker


Physical Review B | 1998

D-D EXCITATIONS AND INTERBAND TRANSITIONS IN MNO : A SPIN-POLARIZED ELECTRON-ENERGY-LOSS STUDY

Bärbel Fromme; U. Brunokowski; E. Kisker


Physical Review Letters | 1995

Resonant exchange scattering in dipole-forbidden d-d excitations in NiO(100).

Bärbel Fromme; Ch. Koch; R. Deussen; E. Kisker


Archive | 2000

d-d Excitations in Transition Metal Oxides - A Spin-Polarized Electron Energy-loss Spectroscopy (Speels) Study

Bärbel Fromme


Physical Review B | 1989

Emission of circularly polarized recombination radiation from p-doped GaAs and GaAs0.62P0.38 under the impact of polarized electrons

Bärbel Fromme; Günter Baum; Dorothee Göckel; Wilhelm Raith


Physical Review B | 2001

Electron exchange in the f − f excitations of EuO

Bärbel Fromme; V. Bocatius; E. Kisker

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E. Kisker

University of Düsseldorf

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C. Bethke

University of Düsseldorf

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M. Möller

University of Düsseldorf

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U. Brunokowski

University of Düsseldorf

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Th. Anschütz

University of Düsseldorf

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V. Bocatius

University of Düsseldorf

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H Bromme

Bielefeld University

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