Diode laser-based cavity ring-down instrument for NO 3 , N 2 O 5 , NO, NO 2 and O 3 from aircraft
Diode laser-based cavity ring-down instrument for NO 3 , N 2 O 5 , NO, NO 2 and O 3 from aircraft
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DOI：
10.5194/amt-4-1227-2011
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发表时间：
2011-06
影响因子：
3.8
通讯作者：
N. Wagner;W. Dubé;R. Washenfelder;C. Young;I. Pollack;T. Ryerson;S. Brown
中科院分区：
文献类型：
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作者：
N. Wagner;W. Dubé;R. Washenfelder;C. Young;I. Pollack;T. Ryerson;S. Brown
抽象。本文介绍了一种基于二极管激光器的腔衰荡光谱仪，用于同时原位测量四种氮氧化物，NO3，N2 O 5，NO，NO2，以及O3，设计用于部署在飞机上。该仪器分别通过662 nm和405 nm处的消光测量NO3和NO2; N2 O 5通过热转化为NO3测量，而NO和O3通过化学转化为NO2测量。该仪器具有几个优点，比以前的仪器由我们的小组开发的测量NO2，NO3和N2 O 5单独的，基于脉冲Nd：YAG和染料激光。首先，连续波二极管激光器的使用降低了对功率和重量的要求，并消除了危险材料。其次，在405 nm处检测NO2比我们以前报道的532 nm仪器更灵敏，并且没有来自O3的可测量干扰。第三，该仪器包括NO和O3到NO2的化学转化，以在两个单独的通道上提供总NOx（= NO + NO2）和Ox（= NO2 + O3）的测量; NO和O3的混合比通过减去NO2来确定。最后，所有五种物质都根据基于254 nm O3吸收的单一标准进行校准，以提供高准确度。缺点包括对662 nm NO3和N2 O 5通道上的水蒸气的敏感性增加，并且与脉冲激光仪器相比，这些物质的敏感性适度降低。NO3和N2 O 5的飞行中检测限均为3 pptv（2 σ，1 s），NO、NO2和O3的飞行中检测限分别为140、90和120 pptv（2 σ，1 s）。在实验室/地面环境中，该仪器的性能大约好2-3倍。NO和NO2的测量精度低于研究级化学发光仪器。然而，这五种物质在一台仪器中的组合，校准到一个单一的分析标准，提供了一个完整和准确的夜间氮氧化物化学的图片。仪器的性能证明，使用最近在加州的现场活动期间获得的数据。
Abstract. This article presents a diode laser-based, cavity ring-down spectrometer for simultaneous in situ measurements of four nitrogen oxide species, NO3, N2O5, NO, NO2, as well as O3, designed for deployment on aircraft. The instrument measures NO3 and NO2 by optical extinction at 662 nm and 405 nm, respectively; N2O5 is measured by thermal conversion to NO3, while NO and O3 are measured by chemical conversion to NO2. The instrument has several advantages over previous instruments developed by our group for measurement of NO2, NO3 and N2O5 alone, based on a pulsed Nd:YAG and dye laser. First, the use of continuous wave diode lasers reduces the requirements for power and weight and eliminates hazardous materials. Second, detection of NO2 at 405 nm is more sensitive than our previously reported 532 nm instrument, and does not have a measurable interference from O3. Third, the instrument includes chemical conversion of NO and O3 to NO2 to provide measurements of total NOx (= NO + NO2) and Ox (= NO2 + O3) on two separate channels; mixing ratios of NO and O3 are determined by subtraction of NO2. Finally, all five species are calibrated against a single standard based on 254 nm O3 absorption to provide high accuracy. Disadvantages include an increased sensitivity to water vapor on the 662 nm NO3 and N2O5 channels and a modest reduction in sensitivity for these species compared to the pulsed laser instrument. The in-flight detection limit for both NO3 and N2O5 is 3 pptv (2 σ, 1 s) and for NO, NO2 and O3 is 140, 90, and 120 pptv (2 σ, 1 s) respectively. Demonstrated performance of the instrument in a laboratory/ground based environment is better by approximately a factor of 2–3. The NO and NO2 measurements are less precise than research-grade chemiluminescence instruments. However, the combination of these five species in a single instrument, calibrated to a single analytical standard, provides a complete and accurate picture of nighttime nitrogen oxide chemistry. The instrument performance is demonstrated using data acquired during a recent field campaign in California.