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Title:First high-resolution analysis of phosgene 35cl2co and 35cl37clco fundamentals in the 250 - 480 cm−1spectral region
Author(s):Kwabia Tchana, F.
Contributor(s):Lafferty, Walter; Flaud, Jean-Marie; Perrin, Agnes; Manceron, Laurent; Ndao, M.
Subject(s):Spectroscopy in Atmospheric Chemistry
Abstract:Phosgene (\chem{COCl_2}) is relatively more abundant in the stratosphere, but is also present in the troposphere in spite of a shorter lifetime (seventy days). Monitoring its concentration by remote sounding of the upper atmosphere is of importance, since some of its strong infrared absorptions, occurring in the important 8-12 $\mu$m atmospheric window, hinder the correct retrieval of Freon-11 concentration profiles\footnote{G. Toon, J.F. Blavier, B. Sen and B.J. Drouin, Geophys. Res. Lett., 28/14 (2001) 2835.}. Indeed, the infrared absorptions used to retrieve this ozone depleting compound occur in the same spectral region. Phosgene, presents two fundamental bands in the 250 - 480 \wn spectral region, with the lowest ($\nu_3$) near 285 \wn. These are responsible for hot bands, not yet analysed but of great importance for accurate modeling of the 5.47 $\mu$m ($\nu_1$) and 11.75 $\mu$m ($\nu_5$) spectral regions and consequently the correct retrieval of Freon-11 atmospheric absorption profiles. High-resolution absorption spectra of phosgene have been recorded at 0.00102 \wn resolution in the 250–480 \wn region by Fourier transform spectroscopy at synchrotron SOLEIL. Due to the spectral congestion, the spectra have been recorded at low temperature (197 K) using a 93.15 m optical path length cryogenic cell\footnote{F. Kwabia Tchana, F. Willaert, X. Landsheere, J.-M. Flaud, L. Lago, M. Chapuis, P. Roy and L. Manceron, Rev. Sci. Inst., 84 (2013) 093101.}. This enables the first detailed far-infrared analyzes of the $\nu_3$ and $\nu_6$ bands of the $^{35}$Cl$_{2}$CO and $^{35}$Cl$^{37}$ClCO isotopologues of phosgene. Using a Watson-type Hamiltonian, it was possible to reproduce the upper state rovibrational infrared energy levels to within the experimental accuracy. The results will be presented in this talk.
Issue Date:2016-06-22
Publisher:International Symposium on Molecular Spectroscopy
Genre:Conference Paper / Presentation
Rights Information:Copyright 2016 by the authors
Date Available in IDEALS:2017-01-26

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