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 Title: FIRST HIGH RESOLUTION ANALYSIS OF THE _21 BAND OF PROPANE AT 921.4 cm_1: EVIDENCE OF LARGE-AMPLITUDE-MOTION TUNNELLING EFFECTS Author(s): Groner, Peter Contributor(s): Lafferty, Walter; Vogt, Natalja; Demaison, Jean; Manceron, Laurent; Flaud, Jean-Marie; Kwabia Tchana, F.; Perrin, Agnes Subject(s): Large amplitude motions, internal rotation Abstract: A high resolution (0.0015 wn) IR spectrum of propane, chem{C_3H_8}, has been recorded with synchrotron radiation at the French light source facility at SOLEIL coupled to a Bruker IFS-125 Fourier transform spectrometer. A preliminary analysis of the $nu_{21}$ fundamental band ($B_{1}$, CH$_{3}$ rock) near 921.4 wn reveals that the rotational energy levels of 21$_{1}$ are split by interactions with the internal rotations of the methyl groups. Conventional analysis of this $A$-type band yielded band centers at 921.3724(38), 921.3821(33) and 921.3913(44) wn for the $AA$, $EE$ and $AE+EA$ tunneling splitting components, respectively.footnote{A. Perrin et al., submitted to $J. Mol. Spectrosc.$} These torsional splittings most probably are due to anharmonic and/or Coriolis resonance coupling with nearby highly excited states of both internal rotations of the methyl groups. In addition, several vibrational-rotational resonances were observed that affect the torsional components in different ways. The analysis of the $B$-type band near 870 wn ($nu_{8}$, sym. C-C stretch) which also contains split rovibrational transitions due to internal rotation is in progress. It is performed by using the effective rotational Hamiltonian method ERHAMfootnote{P Groner, $J. Chem. Phys.$ 107 (1997) 4483; $J. Mol. Spectrosc.$ 278 (2012) 52.} with a code that allows prediction and least-squares fitting of such vibration-rotation spectra. Issue Date: 23-Jun-15 Publisher: International Symposium on Molecular Spectroscopy Citation Info: ACS Genre: CONFERENCE PAPER/PRESENTATION Type: Text Language: English URI: http://hdl.handle.net/2142/79173 Date Available in IDEALS: 2016-01-05
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