A Near-Infared Laser Detector for the Atmospheric Hydroperoxyl Radical

羟基自由基在对流层和平流层的光化学中都起着重要的作用。在对流层中，HO2参与了城市环境中臭氧形成的化学过程。大气中过氧化氢的唯一已知来源是HO2的重组，过氧化氢在酸沉化学中起着重要作用。大气氢氧自由基浓度的直接测量将为测试和改进大气光化学模型提供重要数据。提出的研究将利用近红外二极管激光器在1500 nm附近的光谱波段通过吸收来测量对流层的HO2浓度。由于近红外二极管激光器的高功率和改进的光学特性，与中红外方法相比，这种方法提供了更高的灵敏度。在第一阶段，将进行实验室实验，测量HO2在1500 nm附近的吸收截面。这些实验的结果将为这项技术在对流层测量方面的可行性的关键评估提供基础，并将为第二阶段现场仪器的研制确定关键的设计参数。

The hydroperoxyl radical plays an important role in the photochemistry of both the troposphere and the stratosphere. In the troposphere, HO2 participates in ozone formation chemistry in urban environments. Recombination of HO2 is the only known source of atmospheric hydrogen peroxide, which is important in the chemistry of acid precipitation. Direct measurements of atmospheric hydroperoxyl radical concentrations would provide important data for use in testing and improving models of atmospheric photochemistry. The proposed research will utilize near-infrared diode lasers to measure tropospheric HO2 concentrations by absorption in spectroscopic bands near 1500 nm. This approach offers improved sensitivity, as compared to mid-infrared methods, due to the high power and improved optical characteristics of near-infrared diode lasers. In Phase I, laboratory experiments will be conducted to measure the absorption cross sections of HO2 near 1500 nm. The results of these experiments will provide a basis for critical assessment of the feasibility of this technique for tropospheric measurements and will establish the crucial design parameters for development of field instrumentation in Phase II.