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Toward Detection of FeH+ in the Interstellar Medium: Infrared Multiple Photon Dissociation Spectroscopy of Ar2FeH
Shan Jin1, Jakob Heller1, Christian van der Linde1
1Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstrasse 25, 6020 Innsbruck, Austria.
Abstract:
The iron hydride molecular cation FeH+ is expected to be present in the interstellar medium. Because of the lack of laboratory data, it is yet to be identified in spectrally resolved astronomic observations. As a benchmark for computational predictions and to guide an experimental search for the ro-vibrational lines of FeH+, we performed infrared multiple photon dissociation (IRMPD) spectroscopy of FeH+ tagged with two argon atoms. The Fe-H stretching mode in Ar2FeH+ is observed at 1860 cm-1. Combination bands of the Fe-H stretch with the two Fe-H bending and the asymmetric Fe-Ar stretching modes are observed at 2012 cm-1, 2054 cm-1, and 2078 cm-1. Quantum chemical calculations show that the molecule has C2v symmetry. The Ar-Fe-Ar bending mode at 46 cm-1 is significantly populated at the temperature of the experiment, causing thermal broadening of the Fe-H stretch and its redshift with increasing internal energy.
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