Ambient Level Hydroxyl Radical (OH) Detection Using Broadband Cavity Enhanced Absorption Spectroscopy (BBCEAS) in an Open-Path Configuration

该项目支持开发和测试开放路径、宽带腔基吸收光谱仪（BBCEAS），以测量大气中环境浓度的羟基自由基（OH）。羟基自由基是低层大气中最重要的氧化物质之一，控制着许多气体的大气寿命，并与自然和人为的碳氢化合物发生反应，导致臭氧污染的产生。如果成功，该仪器将提供可用于提高模型准确性的数据，以便在模型和实验测量的OH和挥发性有机化合物（VOC）及其光氧化产物（如臭氧）浓度之间有更好的一致性。为了建立新的仪器来量化OH自由基浓度，需要一个开腔设计。主要研究人员将进行实验，以表征湍流和气溶胶的影响，并包括水平风对使用开腔设计的OH量化的影响。然后，他们将把一个高分辨率光谱仪连接到开放腔BBCEAS仪器上，并在杨百翰大学的大气模拟室中测试仪器和光谱仪/探测器的初始配置。如果仪器能够达到足够的检测极限（LOD），下一步将是在现场进行测试，并将其与测量大气中OH的其他方法进行比较。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

This project supports the development and testing of an open-path, broad band cavity-based absorption spectrometer (BBCEAS) to measure hydroxyl radicals (OH) at ambient concentrations in the atmosphere. Hydroxyl radicals are one of the most important oxidizing species in the lower atmosphere, controlling the atmospheric lifetimes of many gases and reacting with both natural and anthropogenic hydrocarbons leading to the production of pollutant ozone. If successful, this instrument will provide data that can be used to improve the accuracy of models so that there will be better agreement between modeled and experimentally measured concentrations of OH and volatile organic compounds (VOC) and their photooxidation products, such as ozone.In order to build the new instrument to quantify OH radical concentrations, an open-cavity design is required. The principal investigators will conduct experiments to characterize the effects of turbulence and aerosols as well as include the effects of horizontal wind on the quantification of OH using the open-cavity design. They will then interface a high-resolution spectrometer to the open cavity BBCEAS instrument and test the initial configuration of the instrument and spectrograph/detector in the atmospheric simulation chamber at BYU. If the instrument is able to achieve an adequate limit of detection (LOD), the next step will be to test it in the field and intercompare it with other methods for measuring OH in the atmosphere.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.