Low temperature phase shift cavity ring down: Applications to high vibrational overtones

Phase shift cavity ring down (PS-CRD) is a direct absorption technique that due to its long optical path length is an ideal method to obtain high vibrational overtones. Coupling the method to a custom fitted cryostat allows gas phase molecules to be studied at cryogenic temperatures in a thermally isolated vacuum chamber. In this dissertation the nu = 0 → 5 high vibrational overtone measurements of ethane, ethylene, propane, butane, isobutane, and neopentane are presented. Oscillator strengths are calculated and compared to literature values and those obtained in our laboratory using Fourier Transform visible spectroscopy (FT-VIS) with a 6 meter path length White cell. Overtones of methane, CH2D2, and CHD3 are studied at room temperature. Low temperature studies are done for ethane, ethylene, methane, CH2D2, and CHD3. The partially rotationally resolved spectra of the nu = 0 → 5 C-H stretch of CHD3 are shown and analyzed yielding line positions, peak absorptions, and the rotational lines used to obtain the Boltzmann temperature of the gas. The nu = 0 → 4 transition of HD has been obtained at 297 K and 88 K producing line positions and profiles for comparison to literature values as well. Boltzmann temperature calculations are also presented for HD.