Berlin 2012 – wissenschaftliches Programm

Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe

O: Fachverband Oberflächenphysik

O 35: Poster Session II (Polymeric biomolecular films; Nanostructures; Electronic structure; Spin-orbit interaction; Phase transitions; Surface chemical reactions; Heterogeneous catalysis; Particles and clusters; Surface magnetism; Electron and spin dynamics; Surface dynamics; Methods; Electronic structure theory; Functional molecules)

O 35.69: Poster

Dienstag, 27. März 2012, 18:15–21:45, Poster B

A new mode of operation of electron energy loss spectrometers: Application to surface magnon and surface vibration spectra — •Rajeswari Jayaraman, Harald Ibach, and Claus Michael Schneider — Peter Grünberg Institut, Forschungszentrum Jülich, 52425 Jülich, Germany

Using advanced simulations of the electron optics we have found a new mode of operation for the lens system in electron energy loss spectrometers (EELS) in which the cardinal planes of the lenses are closer to the sample. The product of transmission and solid angle angle accepted by the analyzer thereby increases by a factor of 3-5, yielding a corresponding gain in the intensity. The effect is demonstrated for a recently developed high-intensity spectrometer [1] with spectra of surface spin waves on fcc cobalt. Using this new mode we have been able to obtain spin wave spectra with 7meV resolution. Commercially available EEL-spectrometers can likewise be operated in the new mode. We demonstrate this with vibration spectra of water on Ag(115). The electron optical calculations furthermore allow an absolute calibration of the cross section for inelastic electron scattering. [1] H. Ibach, J. Rajeswari, C. M. Schneider, to be published.