Investigations of the Photochemical HONO Formation Reactions of Atmospheric Importance

这项研究的重点是确定大气中亚硝酸的来源。亚硝酸可以形成羟基自由基，一种重要的化合物，负责创造空气污染物臭氧。亚硝酸可以在某些环境表面上，在水和二氧化氮的存在下产生。量化亚硝酸来源对大气的相对重要性将有助于理解空气污染和气候变化的一些原因。本研究的目的是表征和量化亚硝酸（HONO）的光化学来源，HONO是羟基自由基（OH）的重要前体。HONO的光解对大气污染物的氧化和臭氧的产生有重要影响。最近的实验室研究表明，从二氧化氮（NO2）与表面吸附的多酚化合物和随后的表面吸附的硝基酚的光解反应形成的硝基酚可能是HONO的一个重要来源。但波长依赖性HONO产率，从吸附的硝基酚的光解，还没有被表征。 这项工作将量化的光化学HONO和OH的量子产率从非均相和气相光解反应，使用激光光解结合腔衰荡光谱和确定的UV/可见光吸收截面的表面吸附的NO3和硝基酚作为波长的函数，使用布鲁斯特角腔衰荡光谱。其他实验将提供数据的吸收截面的气相硝基酚和HONO产率从硝酸盐和2-硝基苯酚吸附在表面上，作为替代品的各种环境相关的表面。

This research is focused on determining the sources of nitrous acid to the atmosphere. Nitrous acid can form hydroxyl radical, an important compound responsible for creating the air pollutant ozone. Nitrous acid can be produced on some environmental surfaces, in the presence of water and nitrogen dioxide. Quantifying the relative importance of the sources of nitrous acid to the atmosphere will improve the understanding of some of the causes of air pollution and climate change.The objective of this research is to characterize and quantify photochemical sources of nitrous acid (HONO), an important precursor to the hydroxyl radical (OH). The photolysis of HONO significantly influences atmospheric pollutant oxidation and ozone production. Recent laboratory studies have shown that nitrophenols formed from the dark reaction of nitrogen dioxide (NO2) with surface adsorbed polyphenolic compounds and the subsequent photolysis of surface-adsorbed nitrophenols may be a substantial source of HONO. But wavelength-dependent HONO yields, from the photolysis of the adsorbed nitrophenols, have not been characterized. This work will quantify photochemical HONO and the OH quantum yields from heterogeneous and gas phase photolysis reactions using laser photolysis combined with cavity ring-down spectroscopy and determine the UV/visible absorption cross sections of surface-adsorbed NO3 and nitrophenols as a function of wavelength using Brewster angle cavity ringdown spectroscopy. Additional experiments will provide data on the absorption cross sections of gas phase nitrophenols and HONO yields from nitrate and 2-nitrophenol adsorbed on surfaces that serve as surrogates for various environmentally relevant surfaces.