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RESEARCH PRODUCT

High-Resolution Spectroscopy and Preliminary Global Analysis of C–H Stretching Vibrations of C2H4 in the 3000 and 6000 cm-1 Regions

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International audience; Ethylene (ethene, H2C=CH2) is a naturally occurring compound in ambient air that affects atmospheric chemistry and global climate. The C2H4 spectrum is available in databases only for the 1000 and 3000 cm−1 ranges. In this work, the ethylene absorption spectrum was measured in the 6030- 6250 cm−1 range with the use of a high resolution Bruker IFS 125HR Fourierspectrometer and a two-channel opto-acoustic spectrometer with a diode laser. As a secondary standard of wavelengths, the methane absorption spectrum was used in both cases. A preliminary analysis was realized thanks to the tensorial formalism developed by the Dijon group that is implemented in the XTDS software package [Ch. Wenger, V. Boudon, M. Rotger, J.-P. Champion and M. Sanzharov, J. Mol. Spectrosc., 251, 102–113 (2008).]. We considered the two combination bands 5 + 9 and 5 + 11 as an interacting dyad. Parameters for the 9/11 dyad were fitted simultaneously from a re-analysis of previously recorded supersonic expansion jet FTIR data, while parameters for the v5 = 1 Raman level were taken from literature. More than 600 lines could be assigned in the 6030-6250 cm−1 region (and also 682 in the 2950–3150 cm−1 region) and effective Hamiltonian parameters were fitted, including Coriolis interaction parameters. The Dyad features are globally quite well reproduced, even if there are still problems at high J values.