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层中氧气浓度的变化。具体地说，目标是使用差示吸收光谱测量空气中O2摩尔分数的微小变化，甚至达到1ppm。这项研究的动机是希望获得关于大气氧气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、海洋中缺失的氧气的问题，并预测O2和CO2的浓度。这项工作将分为三个阶段：1)半导体激光器和电子噪声消除器的建造和测试；2)建立参照室和样品室，建造气体处理系统，并纳入通过样品氧气室改变光程长度的系统；3)进行测量，以证明该技术的实用性和健壮性。

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.