Hannover 2013 – wissenschaftliches Programm

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A: Fachverband Atomphysik

A 20: Poster: Precision spectroscopy of atoms and ions (with Q)

A 20.7: Poster

Dienstag, 19. März 2013, 16:00–18:30, Empore Lichthof

High resolution fluorescence spectroscopy of Kα transitions in highly charged iron ions at a synchrotron — •Jan Rudolph^1,2, René Steinbrügge¹, Sven Bernitt¹, and José R. Crespo López-Urrutia¹ — ¹Max-Planck-Institut für Kernphysik, Heidelberg, Germany — ²Institut für Atom- und Molekühlphysik, Gießen, Germany

Most prominent features in active galactic nuclei X-ray spectra originate from photoexcited iron K_α transitions. An experimental approach to study these processes needs a high X-ray photon flux near 6.7 keV and a target of highly charged iron ions. For this experiment we used the Heidelberg transportable electron beam ion trap FLASH-EBIT to produce a dense ion target. To resonantly photo excite K_α transitions in this ion cloud and detect fluorescence the PETRA III photon source was used. A double crystal monochromator at beam line P01 provided 10¹²γ s⁻¹ with a resolution of 0.1 eV. By scanning the monochromator energy from 6.4 to 6.7 keV several electric dipole allowed K_α transitions in Fe^17+...24+ ions were detected. Absolute line energies with an accuracy of a few ppm had been measured. Even the natural line width of the fluorescence lines were determined. This method of measuring absolute line energies combining an EBIT with a highly resolved and focused X-ray beam at a synchrotron overcomes classical methods like crystal spectrometer measurements. We achieve higher statistics in a much shorter period of time. The complexity of the measurement setup is reduced compared to classical spectroscopy as well as the susceptibility to disturbances in the experimental surroundings.