Chemical and Spectroscopic Studies of Stratospheric Aerosols

平流层气溶胶的化学和光谱研究

• 批准号: 9321582
• 负责人: Margaret Tolbert
• 金额: $ 35.5万
• 依托单位: University of Colorado at Boulder
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1994
• 资助国家: 美国
• 起止时间: 1994-04-15 至 1998-03-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9321582&HistoricalAwards=false
• 关键词: Chemical; Spectroscopic; Studies; Stratospheric; Aerosols

9321582 Tolbert Chemical reactions on type I polar stratospheric clouds (PSCs) are currently believed to be a key step in polar ozone destruction. Although type I PSCs are thought to be composed of nitric acid/water vapor (HNO3/H2O) mixtures, their exact chemical composition and phase are still uncertain. This research project will use infrared, visible, and ultraviolet spectroscopy to determine the chemical composition of type I PSCs. First, the optical constants for NHO3/H2O mixtures will be measured over a wide wavelength range for use in comparisons with field observations of type I PSCs. Laboratory studies of model type I PSC film growth will also be performed. These studies will use in situ FTIR spectroscopy as a probe of the chemical composition and phase of the condensed material during PSC nucleation and growth. In addition to using spectroscopy to identify PSCs, new spectroscopic experiments will study surface reactions on type I PSCs. The reaction of chlorine nitrate (CIONO2) with hydrochloric acid (HCl) on type I PSCs is currently believed to be the single most important heterogenous reaction promoting ozone loss. Previous work has shown that this reaction depends strongly on the relative humidity is increased. Large angle reflectance FTIR spectroscopy will be used to probe the surface reaction of CLONO2 with HCI on model type I PSC films. Surface spectroscopic probes of the condensed phase during should yield insight into the complex mechanism of this important heterogenous reaction. In addition to chemical reactions on PSCs, there is now heightened interest in heterogenous chemistry on the global stratospheric sulfate aerosol (SSA) layer. Chemical reactions on background and volcanic SSAs may be responsible for the down ward trend in ozone observed in the last decade. This project will investigate the chemical and physical properties of SSAs, composed primarily of sulfuric acid and water vapors (H2SO4) and(H2O). Spectroscopi c experiments will also be performed to characterize low temperature liquid and frozen sulfuric acid films representative of SSAs fro use in comparisons with field observations of SSAs. In addition, the chemical reactivity of SSAs will be studied. A combination of gas phase and condensed phase detection of reactants and products will be used to obtain a more complete picture of the condensed phase reactions. Initial studies will focus on the uptake and reactivity of HOx reservoir species in sulfuric acid as a function of composition and phase of the acid.

小行星9321582 第一类极地平流层云的化学反应目前被认为是极地臭氧破坏的关键步骤。 虽然I型PSC被认为是由硝酸/水蒸气（HNO 3/H2O）混合物组成，但它们的确切化学组成和相态仍然不确定。 该研究项目将使用红外，可见光和紫外光谱来确定I型PSC的化学组成。 首先，NHO 3/H2O混合物的光学常数将在较宽的波长范围内测量，用于与I型PSC的现场观测进行比较。 还将进行I型PSC膜生长模型的实验室研究。 这些研究将使用原位FTIR光谱作为PSC成核和生长期间凝聚材料的化学组成和相的探针。 除了使用光谱学来识别PSC外，新的光谱学实验还将研究I型PSC的表面反应。 硝酸氯（ClONO 2）与盐酸（HCl）在I型PSC上的反应目前被认为是促进臭氧损失的单一最重要的非均相反应。 以前的工作表明，这种反应强烈地依赖于相对湿度的增加。 将使用大角度反射FTIR光谱法来探测CLONO 2与HCl在模型I型PSC膜上的表面反应。 凝聚相的表面光谱探针在此期间应产生洞察这一重要的非均相反应的复杂机制。 除了PSC上的化学反应外，现在对全球平流层硫酸盐气溶胶（SSA）层的非均相化学的兴趣越来越高。背景和火山SSA上的化学反应可能是过去十年中观察到的臭氧下降趋势的原因。 本项目将调查SSA的化学和物理性质，SSA主要由硫酸和水蒸气（H2SO 4）和（H2O）组成。 还将进行光谱实验，以表征代表SSA的低温液体和冷冻硫酸膜，用于与SSA的现场观察进行比较。 此外，将研究SSA的化学反应性。 反应物和产物的气相和凝相检测的组合将用于获得凝相反应的更完整的图像。 初步研究将集中在吸收和反应性的HOx水库物种在硫酸作为一个功能的组成和阶段的酸。