Han Xiao, Li Chenxi, Qi Hongchao, Peng Wei, Chen Ke
School of Optoelectronic Engineering and Instrumentation Science, Dalian University of Technology, Dalian, Liaoning 116024, China.
School of Physics, Dalian University of Technology, Dalian, Liaoning 116024, China.
Anal Chem. 2025 Feb 4;97(4):2518-2524. doi: 10.1021/acs.analchem.4c06355. Epub 2025 Jan 27.
A highly sensitive trace gas sensing system based on carbon black absorption enhanced photoacoustic (PA) spectroscopy (PAS) is reported. A carbon black sheet and a fiber-optic cantilever microphone (FOCM) are integrated to form a fiber-optic cantilever spectrophone (FOCS). The gas concentration is obtained by measuring the acoustic wave amplitude generated by the carbon black sheet, which absorbs the laser passing through the interest gas. Due to the higher laser absorption rate of carbon black than that of flake graphite, the excited solid-state PA pressure wave is enhanced. The ability of the FOCS to detect weak sound waves is related to the laser power and the absorption length. Therefore, an Erbium-doped optical fiber amplifier and a multipass cell are also used to increase laser absorption by the tested gas, which combines with the FOCM to achieve multimechanism enhancement of the system performance. Different from traditional PAS gas detection systems, this system is a noncontact measurement solution, which not only effectively avoids gas flow noise but also makes the sensing element immune to the damage of corrosive gases. The experimental results show that the sensitivity of the system is about four times higher than that of the system using flake graphite as the light-absorbing element. When the average time is 100 s, the minimum detection limit of acetylene is 0.31 ppb. The normalized noise equivalent absorption coefficient of the designed PA system is achieved to be 7.1 × 10 cm·W·Hz.
报道了一种基于炭黑吸收增强光声（PA）光谱（PAS）的高灵敏度痕量气体传感系统。将炭黑片与光纤悬臂麦克风（FOCM）集成，形成光纤悬臂光谱仪（FOCS）。通过测量炭黑片产生的声波振幅来获取气体浓度，炭黑片吸收穿过待测气体的激光。由于炭黑的激光吸收率高于片状石墨，激发的固态PA压力波得到增强。FOCS检测微弱声波的能力与激光功率和吸收长度有关。因此，还使用掺铒光纤放大器和多程池来增加被测气体对激光的吸收，其与FOCM相结合实现系统性能的多机制增强。与传统的PAS气体检测系统不同，该系统是一种非接触式测量解决方案，不仅有效避免了气流噪声，还使传感元件免受腐蚀性气体的损害。实验结果表明，该系统的灵敏度比以片状石墨为吸光元件的系统高约四倍。当平均时间为100 s时，乙炔的最低检测限为0.31 ppb。所设计的PA系统的归一化噪声等效吸收系数达到7.1×10 cm·W·Hz。
