Speaker
Description
Transition metals play a role in astrochemistry, in particular, transition metal complexes are proposed to be astrochemically relevant. Iron is the most abundant transition metal in the interstellar medium (ISM), but only little amounts of pure atomic iron are present.[1] The oxide-hydroxide species [Fe,xO,yH]+, and especially [FeOH]+, are potential iron compounds in the ISM, but spectroscopic data for their identification is not available.
We investigate the structure and properties of three iron oxide-hydroxide cations using infrared multiple photon dissociation (IRMPD) spectroscopy. The experiments are performed using a Fourier Transform Ion Cyclotron Resonance Mass Spectrometer (FT-ICR-MS) at the intra-cavity beam line FELICE of the Free Electron Laser (FEL).[2] We recorded the [Fe,O,H]+, [Fe,2O,H]+, and [Fe,2O,2H]+ spectra in the range from 110 cm–1 to 2000 cm–1. The intense light of the FELICE beam line allows for tag-free spectroscopy of those strongly bound systems. Tag-free spectroscopy is important for comparability with ISM data, as tags influence the spectrum.[3] Several characteristic bands are observed for [Fe,O,H]+, [Fe,2O,H]+, and [Fe,2O,2H]+ species that allow for structural assignments. Rotational substructure is observed in many vibrational modes. The infrared spectra are analyzed with high-level computational chemistry calculations and simulation of rotational structures for obtaining the best match of the band structures.
References
[1] N. Cox, “Allen's Astrophysical Quantities,” Springer New York, 2000.
[2] F. J. Wensink, M. G. Münst, J. Heller; M. Ončák, J. M. Bakker, C. van der Linde, “IR multiple photon dissociation spectroscopy of MO2+ (M = V, Nb, Ta),” J. Chem. Phys. 153, 171101 (2020).
[3] S. Jin, J. Heller, C. van der Linde, M. Ončák, M. K. Beyer, “Toward Detection of FeH+ in the Interstellar Medium: Infrared Multiple Photon Dissociation Spectroscopy of Ar2FeH+,” J. Phys. Chem. Lett. 13, 5867–5872 (2022).
