ABSOLUTE LINE INTENSITIES OF H$_{2}$CO IN THE 3.5 AND 5.7-$\mu$m REGIONS

Abstract

Author Institution: Universite Pierre et Marie Curie-Paris 6; CNRS; Laboratoire de Dynamique, Interactions et Reactivite, UMR 7075, Case Courrier 49, 4 Place Jussieu, 75252 Paris Cedex 05, France; Laboratoire Inter Universitaire des Systemes Atmospheriques (LISA), CNRS, Universites Paris 12 et 7, 61 Avenue du General de Gaulle, 94010 Creteil Cedex, FranceFormaldehyde (H$_{2}$CO) is detected in the earth's troposphere by infrared techniques in the 3.5 and 5.7-$\mu$m regions. Recent measurements produced line positions and relative line intensities}, \textbf{221}, (2003) 192. A. Perrin, A. Valentin, and L. Daumont, \textit{J. Mol. Struct.}, \textbf{780-781}, (2006) 28.} and also IR$\Leftrightarrow$UV line intensity intercomparisons }, in press, (2007).}. 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 H$_{2}$CO were generated by warming paraformaldehyde. An appropriate monitoring of the heating temperature ($\approx$ 40$^{irc}$ C) avoided any polymerization and allowed to obtained a stable pressure of pure H$_{2}$CO (98 $\pm$ 1\%). In this way accurate line positions and absolute intensities of H$_{2}$CO were measured and theoretical modelled in the 3.5 and 5.7-$\mu$m regions leading also to an intercomparison of intensities between the two spectral regions. The determination of self- and N$_{2}$-broadening coefficients is in progress