Detection of tropospheric OH radicals by long‐path differential‐optical‐absorption spectroscopy: Experimental setup, accuracy, and precision
Detection of tropospheric OH radicals by long‐path differential‐optical‐absorption spectroscopy: Experimental setup, accuracy, and precision
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通过长光程差分光学吸收光谱检测对流层 OH 自由基：实验装置、准确度和精密度
DOI：
10.1029/97jd00931
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发表时间：
1997
影响因子：
--
通讯作者：
H. Dorn
中科院分区：
文献类型：
--
作者：
M. Hausmann;U. Brandenburger;T. Brauers;H. Dorn
本文介绍了一种新研制的用于测量对流层OH自由基的长程差分光吸收光谱仪。该仪器由一个高分辨率的梯形光谱仪、一个基长为38.5m的多重反射池和一个提供0.41 nm谱线宽度的紫外光光源组成。可以在总路径长度为1.85或3.1公里的情况下进行局部原位吸收测量。在308 nm附近同时观测到六条大气中的OH旋转吸收线(Q1(2)、Q21(2)、R2(2)、Q1(3)、Q21(3)和P1(1))，使OH测量具有很高的特异性。提出了一种准确确定单个氢氧量测量数据点的精密度和检出限的新方法。目前，2σ的探测极限为1.5×106OH cm−3(基于1.85公里的吸收光程和约6min的积分时间)，相当于最小可探测光密度为2.5×10−5。仪器的绝对精度计算优于6.5%，强调了长程吸收技术作为一种绝对方法的资格。报告了现场试验的例子，以说明目前的性能。
This paper describes a newly developed long-path differential-optical-absorption-spectroscopy instrument used for the measurement of tropospheric OH radicals. The instrument consists of a high resolution echelle spectrometer in conjunction with a multiple-reflection cell of 38.5 m base length and a UV laser light source that provides a spectral line width of 0.41 nm. Local in situ absorption measurements at total path lengths of either 1.85 or 3.1 km can be performed. The simultaneous observation of six atmospheric OH rotational absorption lines (Q1(2), Q21(2), R2(2), Q1(3), Q21(3), and P1(1)) around 308 nm allows OH measurements with high specificity. A new method to accurately determine the precision and the detection limit of each individual OH measurement data point is presented. Presently, a 2σ-detection limit of 1.5×106 OH cm−3 is achieved (based on 1.85 km absorption path length and about 6 min integration time), which corresponds to a minimum detectable optical density of 2.5×10−5. The absolute instrumental accuracy was calculated to be better than 6.5%, which emphasizes the qualification of the longpath absorption technique as an absolute method. Examples of field experiments are reported to illustrate the present performance.