INTERNAL ROTATION ANALYSIS OF THE FTMW AND MILLIMETER WAVE SPECTRA OF FLUORAL (CF3CHO)

Motiyenko, R. A.

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https://hdl.handle.net/2142/100566 Copy

Description

Title

INTERNAL ROTATION ANALYSIS OF THE FTMW AND MILLIMETER WAVE SPECTRA OF FLUORAL (CF3CHO)

Author(s)

Motiyenko, R. A.

Contributor(s)

• Guillemin, J.-C.
• Endo, Yasuki
• Cabezas, Carlos
• Margulès, L.
• Bermúdez, Celina

Issue Date

06/19/18

Keyword(s)

Large amplitude motions, internal rotation

Abstract

To protect atmosphere, hydrofluorocarbons (HFCs) are the current substituents of the dangerous CFCs and other ODS (ozone depleting substances).\footnote{Burkholder J.B. {\em et al.}, Chem.Rev., 2015,~{\bf115}, 3704} Although HFCs are not ODS, they are potent greenhouse gases and, thus, they would be harmful to climate. Consequently, there is a keen interest on monitoring their reaction and the decomposition products in order to measure their effects. Fluoral (trifluoroacetaldehyde, \ce{CF3CHO}) is one of the stable decomposition products of several families of ODS substituents. Monitoring it in the atmosphere is hampered by the few spectroscopic data available in the literature. The rotational spectrum of fluoral from 8-40~GHz was measured previously,\footnote{Woods R.C., 1967, J. Chem. Phys.,~{\bf46}, 4789} however the performed analysis of the spectrum was rather limited due to difficulties in theoretical description. These difficulties reside mainly in the hindered internal rotation of the \ce{CF3} group. Compared to acetaldehyde, in fluoral, the \ce{CF3} group represents the major part of the molecular mass. Therefore, there is a strong coupling between the overall molecular rotation and the internal rotation of the top $\rho=0.92$. As such, previously used principal axis method, where the axes remain unaffected by the large amplitude motion, is not fully suitable for the analysis. We present the analysis of new high resolution microwave and millimeter wave spectra of fluoral in the ranges 6-26 and 50-305~GHz, respectively, employing rho-axis method implemented in RAM36 program. The rotational distortional and internal rotational parameters that reproduce the spectral at experimental accuracy were determined for the ground state and several lowest excited torsional states.

Publisher

International Symposium on Molecular Spectroscopy

Type of Resource

text

Language

English

Permalink

http://hdl.handle.net/2142/100566

DOI

10.15278/isms.2018.TK03

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