High-resolution laser photoacoustic spectroscopy of OCS in the 12000-13000 cm-1 region

A spectrum of natural OCS has been recorded in the near-infrared region using the laser photoacoustic technique. The source is a titanium-sapphire laser pumped by an Ar+ laser. The tunable 1.5 W beam was sent through the photoacoustic cell. This windowless longitudinal resonant cell was designed with two lambda/4 buffer volumes at both ends in order to reduce the noise and so to increase the sensitivity (alpha(min) approximate to 10(-9) cm(-1)). The spectrum of OCS, at a pressure of 90 Torr, has been recorded in the regions 11 953-12 084, 12 829-12 890, and 12 998-13 001 cm(-1). In addition to the 00(0)6-00(0)0 band of (OCS)-O-16-C-12-S-32 recently identified by Ch. Hornberger, B. Boor, R. Stuber, W. Demtroder, S. Naim, and A. Fayt, J. Mol. Spectrosc. 179, 237-245, 1996, new weaker bands have been observed: 04(0)5-00(0)0, 1 10(0)3-00(0)0, 10(0)6-00(0)0, 14(0)5-00(0)0, 02(0)6-00(0)0, and 01(1)6-01(1)0, and also the 00(0)6-00(0)0 band of (OCS)-O-16-C-12-S-34. Effective state parameters are deduced from the band-by-band least-squares fits. The new data have also been introduced in the global analysis which takes into account the l-type resonance and the main anharmonic interactions and so allows a full understanding of the perturbations and the intensity transfers. (C) 1999 Academic Press.