Experimental research on ppb-level ozone detection method based on gas phase chemiluminescence technology

The "ozone hole" and ozone pollution have caused numerous environmental problems that threaten human survival. Therefore, real-time monitoring of the concentration of trace ozone components in the atmosphere is critical. In recent decades, the ethylene chemiluminescence method has become a common method for diagnosing trace ozone in the air due to its high sensitivity, low detection limit, and simple operation. However, this method requires a large amount of high-purity ethylene, which presents risks such as flammability and explosion during actual measurements. Therefore, this paper proposes a new strategy for measuring trace ozone levels at the ppb with high safety and sensitivity, based on the chemiluminescence reaction mechanism between NO and ozone. Firstly, this article designs a system for preparing quantitative ozone standard gas using the principle of plasma discharge and the ultraviolet broadband absorption concentration measurement method; Subsequently, a fluorescence measurement system with high sensitivity and low detection limit was built based on the principle of chemiluminescence and weak light detection technology; Finally, experimental investigations on the chemiluminescence laws of traditional hydrocarbons and NO chemiluminescence laws was conducted with the help of the aforementioned weak light measurement system. The results indicate that the NO chemiluminescence reaction is more prominent than hydrocarbons and is an ideal excitation gas for ozone fluorescence detection. The chemiluminescence signal of NO is approximately 17 times higher than that of C2H4, 68 times higher than that of C2H2, and much higher than that of other hydrocarbons such as CH4, C2H6. The experiment also showed that within the concentration range of 0-10 ppm and103 ppm of NO excitation gas, the measurement system has high linearity and sensitivity, drastically improving the safety and sensitivity of the measurement system. For example, when the NO concentration is 1000 ppm, the correlation linearity coefficient R2 is above 0.999, the lower limit of Allan variance detection can reach approximately 20 ppt.