腔增强吸收光谱技术在大气环境研究中的应用进展

大气污染是全球性环境问题，针对大气环境污染物检测技术的发展对大气环境研究至关重要。光谱分析方法因其具有特异性选择、高精度、高时间分辨等优势，已被广泛应用于大气污染物检测领域。腔增强吸收光谱(CEAS)技术由腔衰荡光谱(CRDS)技术发展而来，是通过测量透过高精细度谐振腔的光强获得分子吸收信息的高灵敏度探测技术。该技术自提出至今二十余年来，因为成本低、操作简单、灵敏度高、适应性强等优势，成为大气环境研究中痕量气体检测的重要手段。介绍了基于相干和非相干光源的两种CEAS技术原理和基本装置构成，其中，采用LED作为光源的非相干宽带腔增强吸收光谱(IBBCEAS)，因其成本更低且能够检测几十纳米带宽的光谱范围，在大气研究领域中应用更加广泛。综述了国内外应用CEAS技术针对大气环境中氮氧化物(NO₂，NO₃，N₂O₅，HONO)、挥发性有机物（甲醛，乙二醛，甲基乙二醛，甲烷，乙烯）、卤素单质(I₂，Br₂)、含卤素化物(OIO，IO，BrO)、臭氧(O₃)及气溶胶等污染物的检测工作。同时，从光源、检测器、光腔结构改进、仪器检测灵敏度优化等多个方面对已有工作进行了全面的归纳总结，重点阐述了其在实验室条件下的检测能力，以及实际大气环境下应用的表现。最后从CEAS技术的系统优化和未来应用趋势方面做出了一定的展望。

Application Progress of Cavity-Enhanced Absorption Spectroscopy (CEAS) in Atmospheric Environment Research

Atmospheric pollution is a global environmental problem, and the development of detection technology for atmospheric environmental pollutants is crucial to atmospheric environmental research. Spectral analysis methods have been widely used in atmospheric pollutant detection because of their specific selection, high accuracy, and high time resolution. Cavity-enhanced absorption spectroscopy (CEAS) is developed from cavity ring-down spectroscopy (CRDS). A high-sensitivity detection technique obtains molecular absorption information by measuring the light intensity through a high-definition resonant cavity. In the past two decades since its introduction, this technology has become an important method for trace gas detection in atmospheric environment research because of its advantages such as low cost, simple operation, high sensitivity, and strong adaptability. This paper introduces the two CEAS technology principles and basic device structure based on coherent and incoherent light sources. Among them, incoherent broadband cavity absorption-enhanced absorption spectroscopy (IBBCEAS) technology mainly uses LED and short-arc xenon lamps as light sources, which has lower cost and can detect the spectral range of tens of nanometers, so it is more widely used in atmospheric research. This paper reviews the application of CEAS technology developed by domestic and foreign research groups detecting nitrogen oxides (NO₂, NO₃, N₂O₅, HONO), volatile organic gases (formaldehyde, glyoxal, methylglyoxal, methane, ethylene), halogen elements (I₂, Br₂), halogen oxides (OIO, IO, BrO), ozone (O₃), aerosol and other pollutants. Meanwhile, in thiswork, we summarized the improvement and optimization of CEAS sensitivity from the aspects of the light source, detector, optical cavity structure. This paper focuses on CEAS detection ability not only under laboratory conditions but also in field campaigns. Finally, some prospects are made from the aspects of system optimization and the future application trend of CEAS technology.