High-resolution laser photoacoustic spectroscopy of HSiF3: The 5 nu(1) and6 nu(1) overtone bands

A spectrum of HSiF3 has been recorded at room temperature with a gas pressu re of 20-50 Torr in the near-infrared region. A laser photoacoustic spectro meter consisting of a longitudinal resonant cell coupled to a titanium:sapp hire ring laser was employed. The 5 nu(1) and 6 nu(1) overtone bands of (HS iF3)-Si-28 associated with the Si-H stretching have been observed at high r esolution (3 x 10(-2) cm(-1)) in the regions 10 900-10 960 and 12 875-12 92 5 cm(-1), respectively. About 450 lines of the 5 nu(1)-0 band have bean ass igned (J less than or equal to 45, K = 3p less than or equal to 18). Within each J cluster of the P and R branches, the K structure has been deconvolu ted. A set of parameters characterizing the upper vibration-rotation struct ure has been obtained. Perturbations have been evidenced for K = 9 and 15. The characterization of the perturbed 6 nu(1)-0 band was limited to J less than or equal to 38, and effective parameters have been determined with no detailed information on the K structure. Most perturbations are supposedly due to the cubic anharmonic constant phi(144) linking n nu(1) to (n - 1)nu( 1) + 2 nu(4) (n = 5, 6) and to their accompanying interacting rovibrational states. (C) 2000 Academic Press.