Date of Thesis
Masters Thesis (Bucknell Access Only)
Master of Science
Karen J. Castle
The rate coefficient for the vibrational self-quenching of carbon dioxide was measured by tunable diode laser absorption spectroscopy using a temperature jump method. Pump-probe spectroscopy was performed using a Nd:YAG laser as the pump laser and a 2300 cm-1 tunable diode laser as the probe laser. The pump laser was used to photolyze ozone molecules and produce a temperature jump, in order to excite carbon dioxide molecules into higher vibrational states. The probe laser was then used to monitor the change in concentration of a particular vibrational state as a function of time due to collisional energy transfer. Three methods were used to analyze the results: fitting the whole transient curve by nonlinear regression fitting, and fitting just the collisional energy transfer region of the transient curve by either a nonlinear regression fit or by solving ordinary differential equations by numerical methods. The rate coefficients were measured over a range of 6 (± 2) × 10-11 to 5 (± 2) × 1013 cm3 s-1 for the first excited state to ground state, 2.7 (± 0.8)× 10-12 to 5 (± 4) × 10-14 cm3 s-1 for the second excited state to first excited state, 2.2 (± 0.8) × 10-12 to 4 (± 2) × 10-13 cm3 s-1 for the third excited state to first excited state, and 9 (± 5) × 10-12 cm3 s-1 for the fourth excited state to the first excited state. There is difference of two to three orders of magnitude between the experimentally measured first excited state to ground state rate coefficient and previously measured values. The disagreement with literature and expected values is likely due to the experimental system being too complex, with too many relaxation processes as well as other energy transfer processes, to measure multiple rate coefficients simultaneously. With changes to the experimental conditions and other energy transfer processes being included in the analysis, these values should improve in future works.
Flynn, Conor J., "Measurement of Carbon Dioxide Vibrational Self-Quenching Rates" (2016). Master’s Theses. 169.