| The first electronically excited state of the oxygen atom (O( 1D)) plays an important role in the atmosphere as a source of odd-hydrogen (HOx) and odd-nitrogen (NOx). The temperature dependent rate coefficients for the reactions of O(1D) with H2O, N2, O2, CO2, N2O, O3 and n-butane (Chapter 3) were measured using a pulsed photolysis-resonance fluorescence apparatus (PP-RF) for the detection of ground state oxygen atoms (O(3P)) as a monitor of the O(1D) reactions. Our results confirm the accuracy of current recommendations for these rate coefficients, one notable exception is O(1D) + N2, where our results (in concert with two recent studies in other laboratories) lead to a new rate coefficient recommendation 15% higher than the current one. Additionally, the rate coefficient for the reaction O(1D) + H2O was measured relative to that with N2 and O 2 (Chapter 4) using a pulsed photolysis-laser induced fluorescence apparatus (PP-LIF) for the detection of the hydroxyl radical (OH). The yield of OH radicals produced per O(1D) + H2O was measured to be . Overall, our results considerably reduce the uncertainty in the calculated atmospheric production rates of HOx and NOx. Lastly, the yield of O(1D) in the 248 nm photolysis of O3 was measured to be independent of temperature (Appendix B).; It has been proposed that the second electronically excited state of the oxygen molecule (O2(1Σg)) may produce significant amounts of HOx and NOx in the atmosphere. The rate coefficients for the reactions of O2(1Σ g) with several atmospherically important gases: O3, H 2O, N2, CO2, CO, CH4, N2O and H2 (Chapter (5), were measured using the PP-RF apparatus. Our results confirm previously reported values for these rate coefficients. In addition, the products of several of the O2(1Σ g) reactions were studied (Chapter 6). Upper limits were placed on the following processes: production of OH and O(3P) from O 2(1Σg) + H2; production of O(3P) and CO2 from O2(1Σ g) + CO; production of NO, NO2 and O(3P), and destruction of N2O, from O2(1Σ g) + N2O. Overall, the results presented in this thesis greatly improve our understanding of the rates of HOx and NOx production in the Earth's atmosphere. |
