Photochemical and Collisional Effects in Trace Atmospheric Species Monitoring

在这个项目中，将进行与监测大气中特定痕量物种的三个主要需要有关的OH自由基的实验室实验。研究OH的A-X电子系统中激光诱导荧光的偏振，以及A态的态到态的转动能量传递的模型，涉及到对流层中的OH本身的探测。A-X体系弱振动带的跃迁概率影响氢氧化物的检测以及大气中氢氧化物动力学的研究。在用Lyman-a湿度计测量平流层H2O时，A态高转动能级的碰撞猝灭以及这一过程的温度依赖性决定了量子产额。HNO3是一种分子，在相对干净的对流层中存在的低水平下很难检测到。SRI科学家研究了在HNO3光解后，在振动和转动能级上新生的OH分布，并将这种分布松弛为热分布。这些数据对于设计用于硝酸监测的光成像/激光诱导荧光方法是必要的。

In this project laboratory experiments on the OH radical pertinent to three major needs for monitoring particular trace species in the atmosphere will be carried out. The study of polarization of laser-induced fluorescence in the A-X electronic system of OH, and the modeling of state-to-state rotational energy transfer in the A-state, concern detection of OH itself in the troposphere. Transition probabilities for weak vibrational bands of the A-X system impact OH detection as well as studies of OH kinetics for atmospheric purposes. Collisional quenching of high rotational levels in the A-State, and the temperature dependence of this process, govern quantum yields in the measurement of stratospheric H2O with a Lyman-a hygrometer. HNO3 is a molecule difficult to detect at the low levels present in the relatively clean troposphere. SRI scientists study the nascent distribution of OH over vibrational and rotational levels, following the photodissociation of HNO3, and the relaxation of this distribution to a thermal one. These data are necessary for the design of a photoframentation/laser-induced fluorescence method for nitric acid monitoring.