15min:

F. KWABIA TCHANA, N. LACOME, Université Pierre et Marie Curie-Paris 6; CNRS; Laboratoire de Dynamique, Interactions et Réactivité, UMR 7075, Case Courrier 49, 4 Place Jussieu, 75252 Paris Cedex 05, France; A. PERRIN, Laboratoire Inter Universitaire des Systèmes Atmosphériques (LISA), CNRS, Universités Paris 12 et 7, 61 Avenue du Général de Gaulle, 94010 Créteil Cedex, France.

Formaldehyde (H₂CO) is detected in the earth's troposphere by infrared techniques in the 3.5 and 5.7-µm regions. Recent measurements produced line positions and relative line intensities\footnoteA.~Perrin, F.~Keller, and J.-M.~Flaud, J.~Mol.~Spectrosc. , \textbf221, (2003) 192. A.~Perrin, A.~Valentin, and L.~Daumont, J.~Mol.~Struct. , \textbf780-781, (2006) 28. and also IR\LeftrightarrowUV line intensity intercomparisons . For atmospheric retrievals absolute intensities and line broadening parameters are needed. For that, new Fourier transform spectra were recorded at high resolution (0.0035~cm^-1) at LADIR in the 1600-3000~cm^-1 spectral region. Low pressures (up to 0.5 torr) of H₂CO were generated by warming paraformaldehyde. An appropriate monitoring of the heating temperature (~ 40^\circ C) avoided any polymerization and allowed to obtained a stable pressure of pure H₂CO (98 \pm 1%). In this way accurate line positions and absolute intensities of H₂CO were measured and theoretical modelled in the 3.5 and 5.7-µm regions leading also to an intercomparison of intensities between the two spectral regions. The determination of self- and N₂-broadening coefficients is in progress.