Laboratory Studies of Tropospheric Sulfur Chemistry

9412237葡萄酒这四年的计划将包括持续的研究，旨在阐明控制硫化物大气氧化的动力学和反应机理，特别是二甲基硫化物(CH3SCH3，二甲基硫)的氧化途径。该计划的目标是最终确定还原的硫化物转化为相对稳定的S(IV)和S(VI)以及二氧化硫(SO2)、硫酸(H2S04)、亚砜、砜和磺酸等产物的速率和机理。强调对活性中间体和稳定最终产物的直接“实时”观察，因为只有通过这种观察才能获得具有独特解释的结果。这项研究将有助于我们理解全球硫循环，从而有助于准确评估生物和人为硫对气候变化(或调节)、能见度降低和酸降水等问题的贡献。具体的实验研究将集中在DMS、DMS加合物、DMSO(CH3SOCH3)、羰基硫化物(OCS)和S03 H2加合物上。实验方法包括将激光闪光光解产生的自由基与一些时间分辨检测技术相结合，包括脉冲激光诱导荧光、原子共振荧光、使用非相干光源和激光光源的紫外可见吸收、红外可调谐二极管激光吸收、光电离质谱仪和共振增强多光子电离质谱仪。在这些机理研究中，获得10-7-10-3 S时间尺度上的时间分辨数据的能力对于确定导致产物形成的详细反应序列至关重要。当然，研究人员将与其他实验室的进展和对流层化学领域的新发展保持同步，并可能在一定程度上改变他们的子任务，以适应新确定的研究需要。***

9412237 Wine This four year program will involve continuing research aimed at elucidating the kinetics and reaction mechanisms which control the atmospheric oxidation of sulfur compounds, with particular emphasis oxidation pathways for dimethylsulfide (CH3 \SCH3, DMS). The goals of the program is the definitive determination of the rates and mechanisms for conversion of reduced sulfur compounds to relatively stable S(IV and S(VI) and products such as sulfur dioxide (SO2), sulfuric acid (H2S04), sulfoxides, sulfones and sulfonic acids. Direct, "real time" observations of reactive intermediates and stable end products is emphasized because only through such observations can results with a unique interpretation be obtained. The research will contribute significantly to our understanding of the global sulfur cycle, thus facilitating accurate assessment of the contribution of both biogenic and anthropogenic sulfur to such problems as climate modification (or regulation), visibility reduction, and acid precipitation. Specific experimental investigations will focus on DMS, DMS adducts, DMSO (CH3SOCH3), carbonyl sulfide (OCS), and S03 H2) adducts. The experimental methodology will involve coupling radical generation by laser flash photolysis with a number of time-resolved detection techniques including pulsed laser induced fluorescence, atomic resonance fluorescence, UV-visible absorption using both incoherent and laser light sources, infrared tunable diode laser absorption, photoionization mass spectrometry, and resonance enhanced multiphoton ionization mass spectrometry. In these mechanistic studies, th ability to obtain time-resolved data on 10- 7-10-3 s time scales is critical to defining the detailed reaction sequences leading to product formation. The investigators will, of course, keep abreast of progress in other laboratories and new developments in the area of tropospheric chemistry, and may alter their sub-tasks somewhat to accomm odate newly identified research needs. ***