Hannover 2013 – wissenschaftliches Programm
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MO: Fachverband Molekülphysik
MO 27: Poster 3: Collisions, Electronic Spectroscopy, Energy Transfer, Quantum Chemistry, Molecular Dynamics, Photochemistry, Spectroscopy in He-Droplets
MO 27.7: Poster
Donnerstag, 21. März 2013, 16:00–18:30, Empore Lichthof
IR-spectroscopy of pyridine and its complexes with water in liquid He nanodroplets — •Melanie Letzner, Pablo Nieto, Torsten Endres, Gerhard Schwaab, and Martina Havenith — Department of Physical Chemistry II, Ruhr University Bochum, Germany
Proton-transfer equilibria are essential for interpreting the physiochemical behavior of basic and acidic compounds in aqueous solution. Here, we investigate the microsolvation of pyridine with water. The simplest complex considered is formed by one water molecule and pyridine. Analysis of this complex gives insight into the way which protonation takes place in larger water clusters. The infrared spectrum of the pyridine-water comlex in the gas phase was observed by Millen and Mines1 and quite recently a detailed Fourier transform IR spectrum was obtained in argon matrix2.We used the Bochum He-nanodroplet machine in combination with an high power IR-OPO (cw: 1.7 W) to investigate pyridine and its complexes with water. Helium nanodroplets provide a soft, suprafluid and ultrcold (0.37 K) matrix that allows to study solvation of pre-cooled moieties. We observed spectral features of pyridine-water aggregates in the region between 3050 cm−1 and 3100 cm−1. The observed pressure dependence of the signals in combination with electric field measurements and calculations allowed the assignment of the signals. The status of the project is presented. References: 1 Destexhe, A., Smets, J., and Adamowicz, L., 1994, J. phys. Chem., 98, 1506. 2 Millen, D. J., and Mines, G. W., 1977, J. chem. Soc. Faraday Trans. ii, 73, 369.