Hannover 2010 – wissenschaftliches Programm
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MO: Fachverband Molekülphysik
MO 10: Poster: Spectroscopy in He Droplets
MO 10.4: Poster
Dienstag, 9. März 2010, 16:00–18:30, Lichthof
IR-spectroscopy of glycine and its complexes with water in liquid He nanodroplets — •Melanie Letzner, Susanne Dohe, Gerhard Schwaab, and Martina Havenith — Department of Physical Chemistry II, Ruhr Universität Bochum, Germany
Glycine is the smallest amino acid, and therefore it is of special interest as a model and starting point for theoretical and experimental studies. Whereas the crystalline form of glycine consists of zwitterions, gas phase glycine is known to exist in the nonionized form. The interaction between glycine and water has been widely studied using a large variety of theoretical methods. Depending on the theoretical level used, a stabilisation of the zwitterionic form is predicted for complexes containing from 2 to 7 water molecules. In low-temperature Ar matrices a set of characteristic IR absorption bands for the zwitterionic form has been observed. The higher stoichiometry complexes (glycine).(H2O)n with n larger than 3 are demonstrated to be zwitterionic H-bonded complexes. The multitude of conformations expected for these glycine-water complexes makes a combination of low temperature and high resolution spectroscopy essential. We want to use the advantages of our experiment to investigate glycine and its complexes with water in helium-nanodroplets at ultracold temperatures in the range from 3000-3800 cm−1. Our measurements were carried out using a high power IR-OPO (cw: 2.7 W) as radiation source and a heliumcluster spectrometer. Helium-nanodroplets are formed by expansion of helium at 55 bar through a 5 µm nozzle which is kept at temperatures of 16 K. The status of the project is presented.