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首页> 外文学位 >Development of an Atmospheric Pressure Laser Induced Fluorimeter (AP-LIF) for Nitrogen Dioxide and Application of AP-LIF for study of Heterogeneous Nitrogen Dioxide Chemistry.
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Development of an Atmospheric Pressure Laser Induced Fluorimeter (AP-LIF) for Nitrogen Dioxide and Application of AP-LIF for study of Heterogeneous Nitrogen Dioxide Chemistry.

机译：常压二氧化氮激光诱导荧光计（AP-LIF）的研制以及AP-LIF在异质二氧化氮化学研究中的应用。

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摘要

Nitrogen dioxide (NO2) is a pollutant of interest for study both because of its controlling role in the oxidant capacity of the atmosphere and the health risks it poses. Concerns about the health effects of NO 2 and its role in forming deleterious atmospheric species have made it desirable to have low-cost, sensitive ambient measurements of NO2 . A continuous-wave laser-diode laser-induced fluorescence (LIF) system for NO2 was developed here which operates at ambient pressure, thereby eliminating the need for an expensive pumping system. The current prototype system has achieved sensitivity several orders of magnitude beyond previous efforts at ambient pressure (limit of detection of 2 ppb, 60 s averaging time). Ambient measurements of NO2 were made in Portland, Oregon using both the standard NO2 chemiluminescence method and the LIF instrument and showed good agreement (r2 = 0.92).;In addition, investigations into surface mediated chemistry involving oxides of nitrogen (namely, NOy) have stimulated new inquiry into potential heterogeneous sources of NO2 as well as challenged the stability of permanent sinks for NO2. The possibility that surface mediated chemistry plays a significant role in NOy chemistry in urban air has for the past few decades received considerable attention. The AP-LIF NO2 instrument is uniquely suited to measure surface chemistry under near ambient conditions.;The so called 'renoxification' reaction of gaseous NO with surface bound HNO3 yielding NO2 (2HNO3(surface) + NO→3NO 2 +H2O(surface)) was suggested as a potentially important source of NO2 which also degraded the stability of nitric acid as a sink of active oxides of nitrogen. Yet, there is disagreement in the literature as to the importance of this reaction. The disagreement stems from differing measurements of the rate for the renoxification reaction. Because there are differences in experimental setups no one research group has studied the renoxification reaction under ambient conditions, i.e., at moderate concentrations of NOy and in a static cell held at 1 atm. In this work, the production of NO2 was measured using a novel AP-LIF. This setup made it possible to measure the rate of production of NO2 due to the heterogeneous reaction of NO with HNO3 under ambient conditions. Under these conditions it was found that renoxification due to gas-phase NO on surface HNO3 is not a significant source of NO2. However, this study did show the importance of water vapor in the renoxification of surface HNO3.
机译：二氧化氮（NO2）是一种值得研究的污染物，这是因为二氧化氮在大气氧化能力中的控制作用及其带来的健康风险。对NO 2的健康影响及其在形成有害的大气物质中的作用的关注使得人们希望获得低成本，灵敏的NO 2环境测量值。此处开发了一种用于NO2的连续波激光二极管激光诱导荧光（LIF）系统，该系统在环境压力下运行，从而消除了对昂贵的泵送系统的需求。当前的原型系统已经实现了比以前在环境压力下的灵敏度高几个数量级的灵敏度（检测极限为2 ppb，平均时间为60 s）。使用标准的NO2化学发光方法和LIF仪器在俄勒冈州的波特兰进行了NO2的环境测量，显示出良好的一致性（r2 = 0.92）。此外，对涉及氮氧化物（即NOy）的表面介导化学的研究激发了对潜在的NO2异质来源的新研究，并挑战了NO2永久汇的稳定性。在过去的几十年中，表面介导的化学在城市空气中的NOy化学中起着重要作用的可能性受到了广泛的关注。 AP-LIF NO2仪器非常适合在近环境条件下测量表面化学性质;所谓的气态NO与表面结合的HNO3的所谓的“再氧化”反应生成NO2（2HNO3（表面）+ NO→3NO 2 + H2O（表面） ）被认为是潜在的重要NO2来源，它也降低了硝酸作为氮的活性氧化物汇的稳定性。然而，在文献中对于这种反应的重要性没有意见。分歧源于对氧化还原反应速率的不同测量。由于实验设置存在差异，因此没有一个研究小组研究过在环境条件下，即在中等浓度的NOy和1atm静态电池中的氧化还原反应。在这项工作中，使用新型AP-LIF测量了NO2的产生。由于在环境条件下NO与HNO3的异质反应，这种设置使得可以测量NO2的生成速率。在这些条件下，已经发现由于表面HNO 3上的气相NO而引起的再氧化不是NO 2的重要来源。但是，这项研究确实表明了水蒸气在表面HNO3的氧化还原中的重要性。

著录项

  • 作者

    Parra, Jeremy.;

  • 作者单位

    Portland State University.;

  • 授予单位 Portland State University.;
  • 学科 Atmospheric Chemistry.;Physics Optics.;Chemistry Analytical.
  • 学位 Ph.D.
  • 年度 2012
  • 页码 107 p.
  • 总页数 107
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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