Publication Date:
2016-01-12
Description:
Methacrolein is a major oxidation product of isoprene emitted in the troposphere. New spectroscopy information is provided with the aim to allow unambiguous identification of this complex molecule, characterized by a large amplitude motion associated with the methyl top. State-of-the-art millimeter-wave spectroscopy experiments coupled to quantum chemical calculations have been performed. For the most stable s-trans conformer of atmospheric interest, the torsional and rotational structures have been characterized for the ground state, the first excited methyl torsional state ( ν 27 ), and the first excited skeletal torsional state ( ν 26 ). The inverse sequence of A and E tunneling sub-states as well as anomalous A-E splittings observed for the rotational lines of v 26 = 1 state clearly indicates a coupling between methyl torsion and skeletal torsion. A comprehensive set of molecular parameters has been obtained. The far infrared spectrum of Durig et al. [Spectrochim. Acta, Part A 42 , 89–103 (1986)] was reproduced, and a Fermi interaction between ν 25 and 2 ν 27 was evidenced.
Print ISSN:
0021-9606
Electronic ISSN:
1089-7690
Topics:
Chemistry and Pharmacology
,
Physics
