Fig. 1. Schematic diagram of photoacoustic spectroscopy detection principle

Fig. 2. Structural optimization of photoacoustic cell

Fig. 3. Schematic diagram of absorption spectra of SF₆，H₂O，and CO₂ in the mid infrared band

Fig. 4. Photoacoustic spectroscopy SF₆ detection system

Fig. 5. Effect of frequency on photoacoustic signals and noise

Fig. 6. Fitting curve of SNR value with frequency variation

Fig. 7. Sensor response time

Fig. 8. Linear response of SF₆ sensor