A Precision Measurement of Atmospheric Oxygen Using Differential-Absorption Spectroscopy

PI计划开发一种技术来测量地球大气中氧气浓度的变化。具体来说，目标是使用微分吸收光谱法测量空气中O2摩尔分数小到1ppm的变化。这项研究的动机是希望获得关于大气氧的短期和长期变化的实验数据，以进一步了解大气、生物圈和海洋中的碳循环；这些数据极有可能有助于回答大气中缺失的碳和海洋中缺失的氧的问题，并预测O2和CO2的浓度。这项工作将分为三个阶段：1)二极管激光器和电子噪声消除器的构建和测试；2)建立参比池和样品池，构建气体处理系统，并纳入通过样品氧池改变光程长度的系统；3)测量以证明该技术的实用性和鲁棒性。

The PI plans to develop a technique to measure changes in the oxygen concentration of the Earth's atmosphere. Specifically, the goal is to measure changes as small as 1 ppm in the O2 mole fraction of air, using differential-absorption spectroscopy. The research is motivated by the desire to obtain experimental data on the short and long-term variations in atmospheric oxygen for further understanding of the carbon cycle in the atmosphere, biosphere, and oceans; it is highly possible that such data would help answer the question of the missing carbon in the atmosphere, the missing oxygen in the oceans, and predict O2 and CO2 concentrations. The work will be split into three phases: 1) construction and testing of a diode laser and an electronic-noise canceller; 2) building the reference and sample cells, contructing the gas-handling system and incorporating the system for changing the optical path length through the sample oxygen cell; and 3) measurements to demonstrate the utility and robustness of the technique.