High-Resolution Laser Photoacoustic Spectroscopy of HSiF(3): The 5nu(1) and 6nu(1) Overtone Bands.

A spectrum of HSiF(3) has been recorded at room temperature with a gas pressure of 20-50 Torr in the near-infrared region. A laser photoacoustic spectrometer consisting of a longitudinal resonant cell coupled to a titanium:sapphire ring laser was employed. The 5nu(1) and 6nu(1) overtone bands of H(28)SiF(3) associated with the Si-H stretching have been observed at high resolution (3 x 10(-2) cm(-1)) in the regions 10 900-10 960 and 12 875-12 925 cm(-1), respectively. About 450 lines of the 5nu(1)-0 band have been assigned (J </= 45, K = 3p </= 18). Within each J cluster of the P and R branches, the K structure has been deconvoluted. A set of parameters characterizing the upper vibration-rotation structure has been obtained. Perturbations have been evidenced for K = 9 and 15. The characterization of the perturbed 6nu(1)-0 band was limited to J </= 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 φ(144) linking nnu(1) to (n - 1)nu(1) + 2nu(4) (n = 5, 6) and to their accompanying interacting rovibrational states. Copyright 2000 Academic Press.