| The high resolution Coherent Anti-Stokes Raman spectrometer at OSU has been used to investigate the ν1 symmetric stretching mode of sulfur trioxide and its 32S, 34S, 16 O, 18O isotopomers. Q-branch structure of this mode was observed at 0.001 cm−1 resolution and a complex band structure was seen for the first time. The modeling of this has required consideration of a subtle combination of Fermi resonance and indirect Coriolis interactions with nearby hidden states; 2ν4(ℓ = 0, ±2), ν 2 + ν4(ℓ = ±1), and 2ν2(ℓ = 0) as well as direct coupling between ν1 and 2ν4(ℓ = ±2). The analysis of the perturbed ν1 spectrum was made possible by locating some of these states via concurrent infrared hot-band studies in a collaboration with Pacific Northwest National Laboratories. Details are presented in this thesis and resultant molecular parameters for 32S16O3 include: ν1 = 1064.59(1) cm−1; α1B = 0.000818(2) cm−1; α1C = 0.000329(5) cm−1; re = 1.41768(12) Å.; In a second application of high-resolution CARS spectroscopy, the linewidths of the Q-branch of the ν2 (C≡C symmetric stretching) mode of acetylene were investigated.; In a second application of high-resolution CARS spectroscopy, the linewidths of the Q-branch of the ν2 (C≡C symmetric stretching) mode of acetylene were investigated. The line broadening and shifts for odd lines J = 7–15 of the Q-branch in the pressure range of 5 to 160 Torr were determined. It was found that the precision of these measurements was limited due to saturation broadening at low pressures. However at higher pressures there was a characteristic linear dependence of linewidth with pressure and hence the broadening coefficients in the range of (122–166) × 10−3 cm−1/amagat were determined. These results have been published in Journal of Raman Spectroscopy, vol. 31, 719–723 (2000). |
