Dresden 2011 – scientific programme
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MO: Fachverband Molekülphysik
MO 32: Poster: Experimental Techniques
MO 32.3: Poster
Thursday, March 17, 2011, 16:00–18:00, P1
Electron detachment spectroscopy on a fast ion beam using a magnetic bottle spectrometer — •Marko Förstel1, Chrisitian Domesle2, Brandon J. Jordon-Thaden2, Lutz Lammich3, Tiberiu Arion1, Melanie Mucke1, Andreas Wolf2, Uwe Hergenhahn1, and Henrik B. Pedersen3 — 1Max-Planck-Institut für Plasmaphysik, EURATOM Association, 85748 Garching, Germany — 2Max-Planck-Institut für Kernphysik, 69117 Heidelberg, Germany — 3Department of Physics and Astronomy, Aarhus University, DK-8000 Aarhus C, Denmark
Electron spectra after photodetachment of O− and OH− in a 4.2 keV fast ion beam were measured by using a magnetic bottle spectrometer and the third harmonic of a Nd:YAG laser. Fast ion beams imply their own approach to the investigation of their physical properties. The broadening of photoelectron lines due to momentum transfer with the emitting ion is an example. In angle-integrating electron spectrometers this effect leads to a substantial line broadening. We introduce a method to overcome this limitation and gain additional information on the angular distribution of the emitted electrons. We simulated the combined effect of the angular distribution function, described by the β-parameter and the velocity shift by momentum exchange. A mapping between β and the lineshape observed in the spectra recorded with a magnetic bottle spectrometer was found. Results determined from an analytical expression and from numerical ray-tracing will be compared to measurements. Spectroscopy of ions at higher photon energies by use of the FLASH Free Electron Laser will be discussed.