CEDAR: RUI--Quenching of Vibrationally-Excited Ozone by Atomic Oxygen

这是一个为期三年的项目，目的是在实验室测量臭氧与基态氧原子碰撞时最低三个振动水平的弛豫速率系数。这些是臭氧遥感数据建模和反演其中间层密度的关键参数。将采用两种独立的实验方法。在第一种方法中，一部分臭氧被266纳米的激光脉冲光解离，产生原子氧并引起温度跳变。当激发态（010）和（001）振动能级的居群达到平衡时，将使用瞬态二极管激光吸收光谱进行监测，从而提供相应弛豫速率系数的信息。为了避免温度跳跃方法的复杂性，第二种方法将涉及用脉冲红外激光直接泵送（001）振动以产生振动激发的臭氧。在室温下进行实验后，将研究150-350 K范围内速率系数的温度依赖性，其中与上层中间层和下层热层区域更为相关。该项目的广泛影响是巨大的。首先，本科生将参与拟进行的研究项目的各个方面，包括实验设计、数据收集、信号处理、电子和计算机接口、数据分析、动力学建模以及在当地专题讨论会和区域或国家科学会议上传播结果。除了在巴克内尔大学的实验室体验外，学生们还将通过这两个小组之间已经建立的合作，在AFRL hanscom AFB从事数据分析和动力学建模活动。在这方面，该提案为本科生提供了独特而优秀的研究经历机会。其次，这些方法和结果在大气化学和臭氧研究中具有普遍的效用，并将大大提高跟踪气候长期变化的能力。

This is a 3-year project is to conduct laboratory measurements of the relaxation rate coefficients for the lowest three vibration levels of ozone in collisions with ground-state oxygen atoms. These are critical parameters in the modeling of ozone remote sensing data and retrieval of its mesospheric density. Two independent experimental methods will be employed. In the first approach, a fraction of ozone is photo-dissociated by a 266-nm laser pulse, generating atomic oxygen and causing a temperature jump. The populations in the excited (010) and (001) vibration levels will be monitored using transient diode laser absorption spectroscopy as they equilibrate, providing information on the corresponding relaxation rate coefficients. To avoid complications from the temperature-jump approach, the second approach will involve direct pumping of the (001) vibration with a pulsed IR laser to produce vibrationally excited ozone. After performing experiments at room temperature, temperature dependence of the rate coefficients in the 150-350 K range, which is more relevant to the upper mesosphere and lower thermosphere region, will be studied. The broader impacts of the project are substantial. First, undergraduate students will be involved in every aspect of the proposed research project, including experimental design, data collection, signal processing, electronics and computer interfacing, data analysis, kinetic modeling, and dissemination of results at local symposia and regional or national scientific meetings. In addition to laboratory experiences at Bucknell University, the students will be engaged in data analysis and kinetic modeling activities at the AFRL hanscom AFB through the collaboration that has already been established between these two groups. In this, the proposal offers unique and excellent opportunities for undergraduate student research experiences. Second, the methods and results have general utility within atmospheric chemistry and ozone research and will lead to greatly improved capabilities to track long term variations in climate.