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 Title: MICROWAVE SPECTROSCOPY OF 2-PENTANONE Author(s): Kleiner, Isabelle Contributor(s): Stahl, Wolfgang; Nguyen, Ha Vinh Lam; Andresen, Maike Subject(s): Large amplitude motions, internal rotation Abstract: Methyl propyl ketone (MPK) or 2-Pentanone is known to be an alarm pheroromone released by the mandibular glands of the bees._x000d_ It is a highly volatile compound. This molecule was studied by a combination of quantum chemical calculations and microwave _x000d_ spectroscopy in order to get informations about the lowest energy conformers and their structures.The rotational spectrum of 2-pentanone was measured using the molecular beam Fourier transform microwave spectrometer in Aachen operating between 2 and 26.5 GHz. Ab initio calculations determine 4 conformers but only two of them are observed in our jet-beam conditions.The lowest conformer has a $C_{1}$ structure and its spectrum shows internal rotation splittings arising from two methyl groups. The internal splittings of 305 transitions for this conformer were analyzed using the XIAM code footnote{ H. Hartwig, H. Dreizler, Z. Naturforsch. 51a, 923 _x000d_ (1996).}. It led to the determination of the values for the barrier heights hindering the internal rotation of two methyl groups_x000d_ of 239 cm$^{-1}$ and 980 cm$^{-1}$ respectively. The next energy conformer has a $C_{s}$ structure and the analysis of the internal splittings of 134 transitions using the XIAM code and the BELGI code footnote{J. T. Hougen, I. Kleiner and M. Godefroid, J. Mol. Spectrosc., 163, 559-586 (1994).} led to the determination of internal rotation barrier height of 186 cm$^{-1}$. Comparisons of quantum chemistry and experimental results will be discussed. Issue Date: 6/20/2017 Publisher: International Symposium on Molecular Spectroscopy Citation Info: APS Genre: CONFERENCE PAPER/PRESENTATION Type: Text Language: English URI: http://hdl.handle.net/2142/97143 DOI: 10.15278/isms.2017.TI07 Date Available in IDEALS: 2017-07-272018-01-29
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