Research on temperature and pressure interference in photoacoustic spectroscopy gas detection

Photoacoustic spectroscopy (PAS) is a highly sensitive optical detection technique for trace gases. However, PAS is sensitive to environmental factors such as temperature and pressure during actual measurement. In this paper, we study the interference characteristics of temperature and pressure in PAS gas detection. The influence of pressure and temperature on PAS is theoretically analyzed based on the basic principle of gas photoacoustic spectroscopy. The effect of different pressure and temperature conditions on the resonance frequency and signal amplitude of PAS is studied through COMSOL software simulation and validated through experiments. Results show that changes in temperature and pressure will affect the resonance frequency and signal amplitude of PAS, thereby impacting the system's sensitivity and accuracy. To reduce the impact of temperature on the PAS sensor, a temperature compensation model was derived based on experimental analysis. Real-time temperature detection is used to compensate for the photoacoustic signal based on temperature changes, which can improve the accuracy and stability of photoacoustic spectroscopy gas detection. For 5% CO2, the photoacoustic signal and experimental temperature data were measured for 3612 s, and after temperature compensation, the detection limit was 0.0192% at an integration time of 365 s, which is 0.0128% higher than before temperature compensation. The system's normalized noise equivalent absorption coefficient is 3.30 x 10-8 cm-1 WHz-1/2. This research improves the accuracy and reliability of photoacoustic spectroscopy gas detection technology and provides useful references for temperature correction in similar gas detection fields.