Stuttgart 2012 – scientific programme
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A: Fachverband Atomphysik
A 27: Poster: Photoionization
A 27.7: Poster
Wednesday, March 14, 2012, 16:30–19:00, Poster.V
The photoabsorption spectrum of O2 below the O 1s threshold reanalysed — •Ralph Püttner1, Catalin Miron2, Kiyoshi Ueda3, and Uwe Becker4 — 1Freie Universität Berlin, Berlin, Germany — 2Synchrotron SOLEIL, Gif-sur-Yvette Cedex, France — 3Institut for Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai, Japan — 4Fritz-Haber-Institut der Max-Planck-Gesellschaft, Berlin, Germany
The photoabsorption spectrum of O2 below the O 1s ionization threshold is known to be complex mainly because of two reason. First, O2 in the ground state has a open-shell structure and second the antibonding O 1sg−1 3 σu∗ resonance is – contrary to most of the other molecules – below the ionization threshold and interacts strongly with the Rydberg states. The resulting complexity initiated in the last three decades numerous experimental and theoretical investigations, which led to a general understanding of the photoabsorption spectra. However, some details are still not fully explained.
In this work we present an extended fit analysis of angular resolved total ion yield spectra, which allowed us to observe novel information. First, we observed Fano lineshapes for the lowest Rydberg state, which is due to an interaction with O 1sg−1 3 σu∗ excitation via the nuclear degree of freedom. Second, two previously unknown and unexpected Rydberg series were identified; these series are probably due to a transition in the coupling scheme of the spins from triplet states of the neutral molecule to doublet and quartet states of the ion.