Analysis of the high resolution absorption spectrum of ethylene between 5800 and 6400 cm-1

The highly congested room temperature absorption spectrum of ethylene (C2H4) is analyzed in the range 5800-6400 cm -1 on the basis of a previously elaborated empirical list of more than 12,200 lines. The investigated spectral interval coincides to a region of weak absorption of water, methane and acetylene. Quantitative information on the relatively strong C2H4 absorption in the region is valuable for trace detection applications. Relying on the position and intensity agreement with a line list of 12C2H4 transitions calculated by the variational method, 1674 transitions could be assigned to five bands (v5+v9, v5+v11, v2+v3 +v11, v2+v6+v9 and v1+v11). All the reported assignments are confirmed by Lower State Combination Difference (LSCD) relations i.e. all the upper states (607 in total) have coinciding determinations of their energies through several transitions (up to 6). The position and intensity comparisons between experiment and theory are discussed together with a comparison to previous works in the region.