Simultaneous Detection of Major Greenhouse Gases with Multiresonator Photoacoustic Spectroscopy

Greenhouse gas (GHG) detection plays an important role in climate change research and industry applications. A novel photoacoustic spectroscopy (PAS) sensor based on multiple resonators has been developed for the detection of GHGs. The major GHGs CO₂, CH₄, and N₂O were measured simultaneously using only one acoustic sensor by coupling three acoustic resonators into a photoacoustic cell. A sinusoidal voltage signal-driven noise source was integrated into a multiresonator photoacoustic cell, allowing convenient calibration of the resonant frequency of the photoacoustic cell. The performance of the sensor was further enhanced by reflecting a laser beam four times in the photoacoustic cell. Allan deviation analysis showed that the minimum detection limits of 2.7 ppm, 90 ppb, and 1 ppb could be achieved for CO₂, CH₄, and N₂O, respectively, over a 300 s integration time. The feasibility of the system was confirmed by continuous measurements of the three major GHGs from different sources for up to 10 h.