Development of Diode-Laser-Based Laser-Induced Fluorescence for in Situ Atmospheric Detection of NO and SO2

小行星9522028 该项目将侧重于开发和优化基于二极管激光器的激光诱导荧光（LIF）系统，用于对流层和平流层中二氧化硫（SO2）的原位检测和定量。 该研究计划将利用二极管激光器和相关光学技术的最新进展，努力构建一种更小，更轻，更有效（更低功耗），更便宜，更灵敏的仪器。 现场测量二氧化硫在超痕量浓度需要解决大气化学中的几个突出问题。 含硫气体在全球对流层化学、局部和区域污染、地球化学硫循环以及对流层和平流层硫酸盐气溶胶的形成中起着重要作用。 主要的人为硫气体是SO2，但没有高灵敏度，快速响应的仪器存在的SO2在低万亿分之一（pptv）浓度范围内的原位检测。 本项目期间将研究的检测方案建议二氧化硫的检测限为2 pptv/sec，尺寸与机载部署平台兼容。 哈佛大学和海军研究实验室的研究人员之间的合作研究最近证明了通过将二极管激光器频率提高四倍来产生SO2 LIF所需的可调谐215-220 nm UV辐射的能力。 进一步的发展，优化，并测试这种基于二极管激光器的紫外线源的性能特点将在此期间进行补助金。 这项持续研究工作的最低目标是在220 nm处获得至少100 uW的平均激光功率，同时保持0.10 cm-1的足够窄的线宽。 今后是否考虑提供资金将取决于能否成功地证明这些最低性能规格。 如果成功的话，荧光检测的通用性和所提出的二极管激光系统的相对宽的可调谐性将允许应用于许多其他分子（例如，一氧化氮）和环境。

9522028 Wofsy This project will focus on the development and optimization of a diode-laser-based, laser-induced fluorescence (LIF) system for in situ detection and quantification of sulfur dioxide (SO2) in the troposphere and stratosphere. The research plan will exploit very recent advances in diode lasers and associated optical technologies in an effort to construct an instrument that is significantly smaller, lighter, more efficient (lower power consumption), less expensive, and more sensitive. In situ measurements of SO2 at ultra-trace concentrations are required to address several prominent issues in atmospheric chemistry. Sulfur-containing gases play important roles in the chemistry of the global troposphere, in local and regional pollution, in the biogeochemical sulfur cycle, and in the formation of sulfate aerosols in both the troposphere and stratosphere. The primary anthropogenic sulfur gas is SO2, but no high-sensitivity, fast response instrument exists for in situ detection of SO2 at the low parts-per-trillion (pptv) concentration range. The detection scheme that will be investigated during this project has a proposed detection limit of 2 pptv/sec for sulfur dioxide and a size compatible with airborne deployment platforms. Collaborative investigations between researchers at Harvard University and the Naval Research Laboratory have recently demonstrated the ability to generate the tunable 215-220 nm UV radiation required for SO2 LIF by frequency quadrupling a diode laser. Further development, optimization, and testing of the performance features of this diode-laser-based UV source will be performed during the course of this grant. The minimum goals of this continuing research effort will be to attain an average laser power of at least 100 uW at 220 nm, while maintaining a sufficiently narrow linewidth of 0.10 cm-1. Consideration for future funding will be contingent on successful demonstration of these minimum performance specifications. If successful, the generali ty of fluorescence detection and the relatively wide tunability of the proposed diode laser system will permit applications to a number of other molecules (for example, nitric oxide) and environments.