# HIGH RESOLUTION ANALYSIS OF $H_{2}CO$ IN THE 3.6 and $4.3 \mu m$ REGION BY FOURIER TRANSFORM SPECTROSCOPY

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 Title: HIGH RESOLUTION ANALYSIS OF $H_{2}CO$ IN THE 3.6 and $4.3 \mu m$ REGION BY FOURIER TRANSFORM SPECTROSCOPY Creators: Perrin, A.; Flaud, J.- M.; Valentin, A.; Camy-Peyret, C.; Brown, L. R. Issue Date: 1999 Publisher: Ohio State University Abstract: Using new Fourier transform spectra recorded at high resolution at LPMA Paris, it has been possible to perform an extensive study of the formaldehyde absorption spectra in the $2600-3000cm^{-1}$ and in the $2200-2500cm^{-1}$ spectral ranges. This analysis was started using the results obtained previously in the same spectral $regions^{a,b}$ and by using the ground state parameters of Bocquet $et al^{c}$ In this way, more than 9000 lines were identified which belong to 10 bands of formaldehyde. From this analysis it appears that these these bands should not be considered as independent. Actually in the high frequency range, the analysis of the strongest bands, namely $\nu_{1}$ and $\nu_{5}$ (symmetric and antisymmetric stretching modes) was complicated by the existence of Fermi-type resonances and by A-type, B-type and C-type Coriolis interactions with various overtone or combination states namely $\nu_{2} +\nu_{6},2\nu_{3},\nu_{2}+\nu_{4},\nu_{3}+\nu_{6}$ and $\nu_{3}+\nu_{4}$. Moreover the analysis was also complicated by additional perturbations due to the weak $2\nu_{4}$ and $2\nu_{6}$ bands and to the very weak $\nu_{4} + \nu_{6}$ band which appear in the low frequency range. The final calculation which involves about 2600 levels belonging to 10 different states leads to rather reasonable results, given the difficulty of the problem. Description: $^{a}$ L.R. Brown, R.H. Hunt, and A. Pine, J. Mol. Spectrosc. 75, 406 (1979). $^{b}$ F. Ito, T. Nakanaga, and H. Takeu, Spectrochimica Acta, 50A, 1397 (1994). $^{c}$ R. Bocquet, J. Demaison, L. Poteau, M. Liedtke, S. Belov, K.M.T. Yamada, G. Winnewisser, C. Gerke, J. Grip and Th. Kohler. J. Mol. Spectrosc. 177, 154 (1996) and J. Demaison (private communication) Author Institution: Laboratoire de Photophysique Mol\'{e}culaire, CNRS, Universit\'{e} Paris Sud; Laboratoire de Physique Mol\'{e}culaire et Applications, C.N.R.S., Universit\'{e} Pierre et Marie Curie; Jet Propulsion Laboratory, California Institute of Technology URI: http://hdl.handle.net/1811/19204 Other Identifiers: 1999-FB-01