# AN ANALYSIS OF THE TORSION-ROTATION-VIBRATION ROTATIONAL SPECTRUM OF THE LOWEST INPLANE BEND AND FIRST EXCITED TORSIONAL STATE OF THE $C_{3v}$ INTERNAL ROTOR $C_{2}H_{5}CN$

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 Title: AN ANALYSIS OF THE TORSION-ROTATION-VIBRATION ROTATIONAL SPECTRUM OF THE LOWEST INPLANE BEND AND FIRST EXCITED TORSIONAL STATE OF THE $C_{3v}$ INTERNAL ROTOR $C_{2}H_{5}CN$ Creators: Pearson, J. C.; Pickett, H. M.; Sastry, K. V. L. N. Issue Date: 1999 Publisher: Ohio State University Abstract: $C_{2}H_{5}CN$ (Propionitrile or ethyl cyanide) is a well known interstellar species abundantly observed in hot cores during the onset of star formation. The onset of star formation generally results in elevated temperature, which thermally populates may low lying vibrational states such as the $206 cm^{-1}$ in-plane bend and the $212 cm^{-1}$ first excited torsional state in $C_{2}H_{5}CN$. Unfortunately, these two states are strongly coupled through a complex series of torsion-vibration-rotation interactions, which dominate the spectrum. In order to understand the details of these interactions and develop models capable of predicting unmeasured transitions for astronomical observations in $C_{2}H_{5}CN$ and similar molecules, several thousand rotational transitions in the lowest excited in-plane bend and first excited torsional state have been recorded, assigned and analyzed. The analysis reveals very strong a- and b-type Coriolis interactions and a number of other smaller interactions and has a number of important implications for other $C_{3V}$ torsion-rotation-vibration systems. The relative importance and the physical origins of the coupling among the rotational, vibrational and torsional motions will be presented along with a full spectroscopic analysis and supporting astronomical observations. Description: Author Institution: Jet Propulsion Laboratory, California Institute of Technology; Department of Physics, University of New Brunswick URI: http://hdl.handle.net/1811/19201 Other Identifiers: 1999-FA-08