Doppler-limited spectra of the CH stretching fundamentals of formaldehyde

Abstract

The Doppler-limited spectrum of H 2CO in the 2700 to 3000 cm −1 region has been recorded using a tunable difference-frequency laser system. This region encompasses the ν 1 and ν 5 fundamental CH stretching bands of formaldehyde as well as a number of strongly interacting combination bands. The tunable laser spectrometer affords complete spectral coverage with a calibration precision better than 10 −3 cm −1 for the transition frequencies and with absolute absorption intensity measurements better than 2%. The band centers for the ν 1 and ν 5 vibrations are measured to be 2782.4572 ± 0.0010 cm −1 and 2843.3254 ± 0.0015 cm −1 respectively, independent of the upper-state rotational constants.