Fig. 1. Simulation results of spectral absorptions of different gases at standard atmospheric pressure

Fig. 2. H₂S gas detection system based on resonant photoacoustic spectroscopy

Fig. 3. Modulation frequency response curve of photoacoustic cell

Fig. 4. Resonance frequency detection results of photoacoustic cell. (a) Frequency response curves of photoacoustic cell at different temperatures;(b) linear relationship between resonance frequency of photoacoustic cell and temperature

Fig. 5. Relationship between photoacoustic signal measured when volume fraction of H₂S is 1000×10^-6 and modulation amplitude

Fig. 6. Detection results of second harmonic signal of H₂S. (a) Photoacoustic second harmonic signal of H₂S; (b) H₂S photoacoustic signal intensity versus volume fraction

Fig. 7. Allan variance measured when volume fraction of H₂S is 1000×10^-6