Hannover 2013 – wissenschaftliches Programm
Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe
MO: Fachverband Molekülphysik
MO 11: Infrared and Microwave Spectroscopy
MO 11.3: Vortrag
Dienstag, 19. März 2013, 11:30–11:45, F 107
High-Resolution Rotational Spectroscopy of polyaromatic molecules and determination of semiexperimental equilibrium structure of 1,3,4 oxadiazole — •Michaela K. Jahn1, Jens-Uwe Grabow1, Don McNaughton2, Jean Demaison3, and Emilio J. Cocinero4 — 1Physikalische Chemie, Leibniz-Universität Hannover, Germany — 2Monash University, Australia — 3Université de Lille I, France — 4Universidad del País Vasco, Spain
1,3,4-Oxadiazole (C2H2N2O) is a five membered heterocyclic molecule, which appears as building block in a variety of pharmaceutical drugs. A spectroscopic analysis, aming at the precise stucture of the molecular unit, employed Fourier transform microwave spectroscopy of a supersonic jet observing the main and minor isotopologues in natural abundance. The extremely high resolution of the FTMW-instrument yields precise spectrocopic constants, including all elements of the nitrogen nuclear quadrupole coupling hyperfine tensors. Due to the large rotation of the principal axis system upon isotopic substitution, the determination of the equilibrium structure is poisoned by vibrational effects. Reliable structures employing a combination of ab-initio results at different levels in approaches called iteratively reweighted fit, mixed regression and extrapolated structures. Additionally, for some polyaromatic, nitrogen containing systems, we show that quantum chemical predictictions, employing DFT calculations with inexpensive basis sets, already compare well with the measured microwave spectra. The results of our rotational analysis provide the transition frequencies as prerequisite for deep radio astronomical searches in space.