Medium resolution infrared grating spectra of gaseous ketene, H2CCO were recorded between 1000 and 400 cm-1, both at instrument temperature (40°C) and with cooling (-40°C). Interferometric Fourier spectra were also measured at -70°C with resolution 0.22 cm-1 between 450 and 330 cm-1. The K structure of the fundamentals ν5, ν6, ν8, and ν9 was assigned. These fundamentals are coupled by a-axis Coriolis interactions. These couplings were analysed on the symmetric top basis for setting up the perturbation matrix and by utilizing the K-dependent Coriolis shifts of levels. A preliminary analysis of the Coriolis intensity anomalies was also undertaken. Band center values from combination differences are ν50 = 587.30 (27) and ν60 = 528.36 (39) cm-1. Synthetic spectra indicate the band origins of ν8 and ν9 to be close to 977.8 and 439.0 cm-1, respectively. Estimates of Coriolis coupling constants obtained from synthetic spectra are ζ58a = + 0.33 (5), ζ68a = + 0.714 (20), ζ59a = - 0.774 (20), and ζ69a = - 0.30 (2). Approximate ratios of unperturbed vibrational transition moments obtained from spectral simulations are M80:±iM50:±iM60:M90 ≈ +2:-9:+10:+0.5.
ASJC Scopus subject areas
- Atomic and Molecular Physics, and Optics
- Physical and Theoretical Chemistry