Mainz 2017 – wissenschaftliches Programm
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MO: Fachverband Molekülphysik
MO 9: Posters 1: Dichroism, VUV and Xray, Clusters, and Cold Molecules
MO 9.13: Poster
Dienstag, 7. März 2017, 17:00–19:00, P OG1
Untangling the far-infrared/fingerprint region of the absorption spectrum of small water clusters using helium droplet spectroscopy — •Raffael Schwan1, Devendra Mani1, Nitish Pal1, Gerhard Schwaab1, Britta Redlich2, Lex van der Meer2, and Martina Havenith1 — 1Physikalische Chemie II, Ruhr-Universität Bochum — 2Institute for Molecules and Materials (IMM), Radboud University Nijmegen
The molecular understanding of water-water interactions has been subject of numerous experimental and theoretical studies. The intramolecular modes of water clusters (H2O)n with n ≤ 6 are well investigated in the mid-infrared and in the fingerprint region while there are only few experimental studies treating the far-infrared region. This region is mainly dominated by intermolecular motions. The most prominent one is the librational band ranging from 300 to 1000 cm−1 in H2O.
Recently, we have combined our helium droplet spectrometer with the free electron laser at the FELIX facility, Radboud University Nijmegen. Helium droplets provide a soft matrix suited well for spectroscopic investigations. They enable the step-wise formation and stabilization of weakly bound aggregates at low temperatures of 0.37 K. In combination with mass selective and pressure dependent measurements, helium droplet spectroscopy becomes a powerful tool for assigning spectral signals to distinct aggregates. Here, we show the absorption spectra of small water clusters in the frequency range of the FELIX radiation source and their assignment based on pressure dependent measurements and accompanying calculations.