All-Optical Photoacoustic Spectroscopy-Based Dual-Component Greenhouse Gas Analyzer

• Published in: Analytical chemistry (Washington) 2024-09, Vol.96 (37), p.14819-14825
• Main Authors: Guo, Min, Zhou, Mengda, Yang, Beilei, Zhao, Xinyu, Li, Chenxi, Yu, Qing, Zhang, Guangyin, Fang, Zebo, Chen, Ke
• Format: Article
• Language: English
• Subjects: Acoustic resonance; Cantilever beams; Carbon dioxide; Detection limits; Fiber optics; Gas analyzers; Greenhouse gases; Methane; Photoacoustic cells; Photoacoustic spectroscopy; Resonance; Sensitivity analysis; Signal reflection; Spectroscopic analysis; Spectroscopy
• ISSN: 0003-2700; 1520-6882; 1520-6882
• DOI: 10.1021/acs.analchem.4c02440

To achieve high sensitivity detection of dual-component greenhouse gases carbon dioxide and methane simultaneously, a multimechanism synergistic enhanced all-optical photoacoustic spectroscopy gas analyzer is presented. The acoustic resonance of the photoacoustic cell and the mechanical resonance of a fiber-optic cantilever acoustic sensor are used to enhance the photoacoustic signals of the dual-component gas. The optimized multipass beam reflection structure enhances the effective excitation power of the dual-component gas. The highly sensitive detection of carbon dioxide and methane at dual-frequency operating points is realized by dual-channel laser modulation combined with dual-input digital lock-in amplification technology. The Allan–Werle deviation analysis results show that with a 100 s average time, the minimum detection limits of carbon dioxide and methane are 76.5 and 1.9 ppb, respectively. The corresponding normalized noise equivalent absorption (NNEA) coefficients are 3.1 × 10–10 and 2.9 × 10–10 cm–1 W/Hz1/2, respectively.