The overtone spectrum of carbonyl sulfide in the region of the ν1+4ν3 and 5ν3 bands by ICLAS-VECSEL

The high-resolution overtone spectrum of OCS has been recorded in the region of the v(1) + 4v(3) and 5v(3) bands by intracavity laser absorption spectroscopy based on an optically pumped vertical external cavity surface emitting laser (VECSEL). The extremely weak v(1) - 4v(3) band at 8954.87cm(-1) was found to be isolated. The 5v(3) band at 10080.91 cm(-1) is accompanied by two weaker bands at 9933.53 and 10114.02 cm(-1) assigned to the 12(0)4-00(0)0 and 04'4-00'0 bands, respectively. In addition, the 01(1)5-01(1)0 hot band was detected together with the extremely weak band heads of the R branch of the 02(0,2)5-02(0,2)0 hot bands. Finally, the 5v(3) band of the (OCS)-O-16-C-12-S-34 minor isotopomer, present in natural abundance in the sample, was also observed and rotationally analyzed. Effective state parameters could be retrieved by standard band-by-band rotational fitting of the line positions, leading to a typical rms of 0.006cm(-1). The observed line positions were compared to the predictions of the global model described by Rhaibi et al. [J. Mol. Spectrosc. 191 (1998) 32-44]. In general, the agreement is excellent, close to the experimental uncertainty (0.01 cm(-1)) thus confirming the high predictive ability of this effective Hamiltonian model. Weak but significant deviations up to 0.1cm(-1) were, however, identified for two rotational levels of the highly excited 2,16(0),0 dark state, observed through a local interaction with the 0005 state. In the case of the (OCS)-O-16-C-12-S-34 isotopomer, the predicted line wavenumbers of the 5v(3) band were globally overestimated by about 0.04cm(-1). The new data have been included in the corresponding global model, leading to almost unchanged values of the molecular parameters and a statistical agreement with the experiment. (C) 2003 Elsevier Science (USA). All rights reserved.