Stuttgart 2012 – wissenschaftliches Programm
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MO: Fachverband Molekülphysik
MO 16: Collisions and Spectroscopy in He-Droplets
MO 16.5: Vortrag
Donnerstag, 15. März 2012, 11:30–11:45, V38.02
Study on the pyridine aggregation in helium nanodroplets — •Pablo Nieto, Torsten Poerschke, Daniel Habig, Gerhard Schwaab, and Martina Havenith — Department of Physical Chemistry II, Ruhr-University, 44780 Bochum, Germany
Pyridine crystals show the unusual property of isotopic polymorphism. Experimentally it has been observed that deuterated pyridine crystals exist in two phases while pyridine does not show a phase transition [1]. Therefore, although isotopic substitution is the smallest possible modification of a molecule it greatly affects the stability of pyridine crystals. A possible experimental approach in order to understand this striking effect might be the study of pyridine aggregation for small clusters. By embedding the clusters in helium nanodroplets the aggregates can be stabilized and studied by means of Infrared Depletion Spectroscopy.
Pyridine small clusters were identified in the C-H asymmetric vibration region (3000-3100 cm−1) using this method. The number of molecules of the clusters responsible of the different bands were identified by means of pickup curves measurements as well as mass sensitive detection of the clusters. Investigations with stark field measurements will be also discussed.
[1] S. Crawford et al., Angew. Chem. Int. Ed., 48, 755 (2009)