The Rotationally-Resolved Absorption Spectrum of Formaldehyde from 6547 to 7051 cm^-1

We report new experimental data on the rotationally resolved room temperature absorption spectrum of CH₂O in the near infrared (NIR) region between 6804 and 7051 cm^-1 (1470-1418 nm). Data have been obtained by cavity enhanced absorption spectroscopy and complement the spectrum in the wavelength range 6547-6804 cm^-1, obtained using virtually the same experimental set-up and already published in an earlier publication (Staak et al., J. Mol. Spectrosc. 229 (2005) 115-121). Several vibrational combination bands occur in this region and give rise to a congested spectrum and over 4500 lines with cross-sections over 5 × 10^-23 cm² were observed. Recent experimental studies using NIR absorption spectroscopy for quantifying CH₂O in different chemical systems indicate that the absorption cross-sections obtained by Staak et al. may have been overestimated. The results of these experiments are reviewed here and a recommendation for absolute absorption cross sections of CH₂O in the NIR range will be given. Absolute absorption cross-sections stated here are corrected by the recommended factor.