The high-resolution infrared spectrum of ethylene in the 1800–2350 cm⁻¹spectral region

Abstract

Fourier transform spectra of ethylene (C 2 H 4) have been recorded in the 1800 cm-1 to 2350 cm-1 (4.3 µm to 5.6 µm) spectral region using a Bruker IFS125HR spectrometer at a resolution of 0.004 cm-1 leading to the observation of six vibrational bands, ν 7 + ν 8 , ν 4 + ν 8 , ν 6 + ν 10 , ν 6 + ν 7 , ν 4 + ν 6 and ν 3 + ν 10. The corresponding upper state ro-vibrational levels were fit using a Hamiltonian matrix accounting for numerous interactions. A satisfactory fit could be obtained using a polyad of nine interacting states {8 1 10

First theoretical global line lists of ethylene (12C2H4) spectra for the temperature range 50−700 K in the far-infrared for quantification of absorption and emission in planetary atmospheres

“…Integrated band intensities from low-resolution spectra have been measured by Lebron & Tan (2012). Few works in the literature were devoted to absolute intensity measurements in rotationally resolved spectra (Blass et al 2001;Rotger et al 2008;Vander Auwera et al 2014;Lafferty et al 2011;Ben Hassen et al 2012); Alkadrou et al (2016) but ethylene line-by-line intensity data above 3 µm range are essentially missing.…”

“…Many line-by-line analyses have focused on the 10 µm region using spectroscopic empirical models (Blass et al 2001;Rotger et al 2008;Vander Auwera et al 2014;Tan et al 2000;Ulenikov et al 2013); Alkadrou et al (2016), either for each band individually or simultaneously for the so-called tetrad ν 10 /ν 4 /ν 7 /ν 12 . Analyses of high-resolution Fourier transform spectra in the 4.3−5.6 µm region were reported by Lafferty et al (2011), Ben Hassen et al (2012. This included the six vibrational bands ν 7 + ν 8 /ν 4 + ν 6 /ν 6 + ν 10 /ν 6 + ν 7 /ν 4 + ν 6 /ν 3 + ν 10 .…”

“…This spectral range has been analyzed in Lafferty et al (2011), Ben Hassen et al (2012 but is not included in the current HITRAN database. The strongest absorption corresponds to the combination bands as ν 7 +ν 8 , ν 6 +ν 10 , ν 4 +ν 8 or ν 3 +ν 10 .…”

“…1, we plot only a small part (J < 35) of our variationally predicted reduced energy levels E vJ − E r.r. and compare them to those assigned from analysis (Blass et al 2001;Rotger et al 2008;Vander Auwera et al 2014;Ulenikov et al 2013;Lafferty et al 2011;Ben Hassen et al 2012); Alkadrou et al (2016). To match the scale of the figure, all levels were shifted by the values of the rigid rotor energy levels E r.r.…”

Precise ro-vibrational analysis of molecular bands forbidden in absorption: The ν8+ν10 band of the 12C2H4 molecule

“…Table 1 presents the list of the lowest vibrational bands of ethylene, 12 C 2 H 4 (below 2000 cm À1 from Refs. [12,13,[31][32][33][34]), together with their symmetry. The last is especially important because the bands of the symmetry B 1u ; B 2u , or B 3u are allowed in absorption from the ground vibrational state.…”