Wavenumbers, line strengths, and assignments in the Doppler-limited spectrum of formaldehyde from 2700 to 3000 cm −1

Abstract

The spectrum of H 2CO from 2700 to 3000 cm −1 has been examined at Doppler-limited resolution using a tunable difference frequency laser spectrometer at Lincoln Laboratory. The wavenumbers and strengths of 4350 absorptions have been determined with an accuracy of 0.001 cm −1 and 5%, respectively. These data have been incorporated into the analysis of lower-resolution data from Florida State University to assign 72% of the observed absorptions to one of seven bands: ν 3 + ν 4 (a C-type band at 2655 cm −1), ν 3 + ν 6 (a B-type band at 2719.156 cm −1), ν 1 (an A-type band at 2782.457 cm −1), ν 5 (a B-type band at 2843.326 cm −1), ν 2 + ν 4 (a C-type band at 2905 cm −1), 2 ν 3 (an A-type band at 2999.5 cm −1) and ν 2 + ν 6 (a B-type band at 3000.066 cm −1). The band ν 3 + ν 4 has been observed for the first time, and the band center for 2 ν 3 has been corrected from a value of 2972 cm −1 to the value listed above. The effects of strong Fermi and Coriolis resonances on the spectra are discussed.