Cao Yuan, Liu Kun, Wang Ruifeng, Chen Weidong, Gao Xiaoming
Opt Express. 2021 Jan 18;29(2):2258-2269. doi: 10.1364/OE.412922.
Aerosol optical absorption measurements are important for the prediction of climate change, as aerosols directly disturb Earth's radiation balance by absorbing or scattering solar radiation. Although photoacoustic spectroscopy is commonly recognized as one of the best candidates to measure the absorption of aerosols, multi-wavelength measurements of aerosols optical absorption remain challenging. Here, a method based on photoacoustic spectroscopy that can simultaneously measure the aerosol absorption characteristics of three wavelengths (404, 637 and 805 nm) is proposed. In the three-wavelength photoacoustic spectrometer (TW-PAS), a photoacoustic cell with three acoustic resonators operating at different resonant frequencies was designed for offering multi-laser (multi-wavelength) operation simultaneously, and only one microphone was used to measure the acoustic signals of all resonators. The performance of TW-PAS was demonstrated and evaluated by measuring and analyzing the wavelength-dependent absorption coefficients of carbonaceous aerosols, which shows good agreement with previously reported results. The developed TW-PAS exhibits high potential for classifying and quantifying different types of light-absorbing aerosols by analyzing its absorption wavelength dependence characteristics.
气溶胶光学吸收测量对于气候变化预测至关重要，因为气溶胶通过吸收或散射太阳辐射直接干扰地球的辐射平衡。尽管光声光谱法通常被认为是测量气溶胶吸收的最佳方法之一，但气溶胶光学吸收的多波长测量仍然具有挑战性。在此，提出了一种基于光声光谱法的方法，该方法可以同时测量三个波长（404、637和805纳米）的气溶胶吸收特性。在三波长光声光谱仪（TW-PAS）中，设计了一个带有三个以不同共振频率运行的声学谐振器的光声池，用于同时提供多激光（多波长）运行，并且仅使用一个麦克风来测量所有谐振器的声学信号。通过测量和分析碳质气溶胶的波长相关吸收系数，证明并评估了TW-PAS的性能，其与先前报道的结果显示出良好的一致性。通过分析其吸收波长依赖性特征，所开发的TW-PAS在对不同类型的吸光气溶胶进行分类和定量方面具有很高的潜力。
