High Precision Oxygen Isotope Ratio Measurements in Atmospherically Important Reactions and in Air Species

拟议的研究代表了对对流层和平流层化学具有直接重要性的大气物质和反应的同位素测量的延续。 PI 建议执行五项单独的任务：（1）Troe 等人最近的动力学测量。对于 O O2 M 重组已表明，在压力达到 1,000 bar 的压力下，速率常数以不可预测的方式变化，这可能与 O3 形成和平流层中的异常 18O、17O 分馏有关，目前尚不清楚。 提出了高压、变温、浴气体实验来解决电子激发和自由基复杂机制对 O3 形成中同位素分馏的作用，并定义 O3 形成中与质量无关的氧同位素分馏过程的机制。 (2) 使用目前开发的实验和理论技术，PI 建议测量 O3-O2-O 与 CO2、H2O、N2O 和 CO 之间的同位素交换速率。平流层 O3、H2O 和 CO2 中存在异常大量的 18O 富集，但尚不清楚。 没有测量模拟这些反应所需的大部分同位素交换率。 (3)PI在O3的热分解中发现了新的同位素效应。 他建议解决这一机制，因为它对于一般同位素分馏过程和化学反应非常重要。 (4) 测量了大气 CO2 中可变的 17O/18O 比率，PI 已证明该比率可通过 CO2-H2O 交换去除。 确定变量 17O/18O 的来源并探索作为 CO2-H2O 交换和一般混合寿命的定量测量的应用，例如 计划进行平流层-对流层交换 (5) 将专门维持高精度 18O 对流层 O2 测量，以验证圣安娜条件下的 18O 变化并测量平流层 O2 样本。

The proposed research represents a continuation of isotopic measurements of atmospheric species and reactions of direct importance to tropospheric and stratospheric chemistry. The PI proposes to conduct five individual tasks: (1) Recent kinetic measurements by Troe et al. for O + O2 + M recombination have shown that, at pressures to 1,000 bar pressure, the rate constant varies in an unpredicted fashion which may be related to the anomalous 18O, 17O fractionation in O3 formation and in the stratosphere, which is presently not understood. High pressure, variable temperature, bath gas experiments are proposed to resolve the role of electronic excitation and radical complex mechanisms upon isotopic fractionation in O3 formation and to define the mechanism of the mass independent oxygen isotopic fractionation process in O3 formation. (2) Using presently developed experimental and theoretical techniques, the PI proposes to measure the rate of isotopic exchange between the species O3-O2-O and CO2,H2O, N2O and CO. Anomalously large 18O enrichments exist in stratospheric O3,H2O and CO2, but which are not understood. There are no measurements of most of the isotopic exchange rates needed to model these reactions. (3) The PI has found a new isotope effect in the thermal decomposition of O3. He proposes to resolve this mechanism as it is of importance to general isotopic fractionation processes and chemical reactions. (4) A variable 17O/18O ratio in atmospheric CO2 has been measured, which the PI has demonstrated is removed by CO2- H2O exchange. Determination of the source of the variable 17O/18O and exploration of applications as a quantitative measure of the lifetime of CO2-H2O exchange and general mixing, e.g. stratospheric-tropospheric exchange are planned (5) High precision 18O tropospheric O2 measurements will be maintained specifically to verify 18O variations in Santa Ana conditions and measure stratospheric O2 samples.