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

拟议的研究是对大气物种和对对流层和平流层化学具有直接重要性的反应的同位素测量的继续。国际和平研究所建议进行五项单独的任务：(1)特罗伊等人最近的动力学测量。对于O_2O_2-M复合的研究表明，在1,000巴的压力下，速率常数以一种不可预测的方式变化，这可能与O_3地层和平流层中18O、17O的异常分馏有关，这一点目前尚不清楚。提出了高压、变温、浴气实验，以解决电子激发和自由基复杂机制在臭氧地层中对同位素分馏的作用，并确定了臭氧地层中氧同位素分馏过程的质量无关机制。(2)利用目前发展的实验和理论技术，PI提出了测量物种O_3-O_2-O与CO_2、H_2O、N_2O和CO之间的同位素交换速率。平流层O_3、H_2O和CO_2中存在异常大的~(18)O丰度，但尚不清楚。没有对这些反应建模所需的大部分同位素交换率的测量。(3)等电点在臭氧的热分解过程中发现了新的同位素效应。他建议解决这一机制，因为它对一般的同位素分馏过程和化学反应很重要。(4)测定了大气CO_2中17O/18O的变化比，证明该等电点是通过CO_2-H_2O交换去除的。确定17O/18O变量的来源，探索作为二氧化碳-H2O交换和一般混合寿命的定量计量的应用，例如计划进行平流层-对流层交换(5)将专门保持18O高精度对流层O2测量，以核实圣安娜条件下18O的变化并测量平流层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.