Spectroscopic investigation of vibration-rotation bands in acetaldehyde: Focus on the n nu(3) (n=1-5) aldehyde CH stretch bands

We describe experiments on acetaldehyde ((CH3CHO)-C-12-C-12-O-16) resulting in new or improved spectroscopic data on the n nu(3) (n = 1-5) aldehyde CH stretching vibrational bands. The n = 1 component is rotationally resolved using room temperature and supersonic jet Fourier transform spectroscopy, and vibration-rotation assignments are reported. The next two components (n = 2, 3) are recorded at room temperature using Fourier transform spectrosc opy, and the K-structure is resolved and assigned. The last two series of b ands (n = 4, 5) are observed but not resolved, using laser opto-acoustic sp ectroscopy. Effective vibrational constants (<(omega)over tilde>(eff)(3) = 2938.53 cm(-1), x(33)(eff) = 55.75 cm(-1)) are obtained. Information is als o provided on additional bands in the spectrum from 1300 to 14 000 cm(-1), involving, in particular, the assignment of the K-structure in nu(11) and 2 nu(1), from the jet-cooled and the room-temperature Fourier transform spec tral data, respectively. A table updating the origin of most vibration-rota tion bands in acetaldehyde previously assigned in the literature is provide d. (C) 1999 Elsevier Science B.V. All rights reserved.