Development of Carbon Dioxide Detection Device Based on Mid-Infrared Cavity Decay Spectroscopy Technology

With the rapid development of the nuclear industry, the amount of waste to be treated and monitored increases, and the potential emissions will also increase, and C-14 needs to be monitored. C-14 produced by nuclear facilities is mainly combined with CO₂, so sensitive monitoring of ¹⁴CO₂ gas is of great significance. In this paper, cavity ring-down spectroscopy (CRDS) is used to detect the CO₂ absorption spectrum by selecting the center wave number of ¹⁴CO₂ absorption line around 2209.11 cm⁻¹. A CO₂ detection system based on mid-infrared cavity ring-down spectroscopy is developed by using a quantum cascade laser in mid-infrared band, an optical resonator, and a reasonable optical path design and gas pipeline design. Based on the developed system, different concentrations of CO₂ (0.5%-1.3%) were detected, and the experimental data were fitted and analyzed, and the results were found to be consistent with the theoretical formula, which confirmed the feasibility of the developed mid-infrared cavity ring-down spectrum system. The system has successfully realized the accurate measurement of different concentrations of CO₂ gas in the mid-infrared band, the absorption spectrum of ¹⁴CO₂ was measured by mid-infrared cavity ring-down technique, which provides an important technical support and foundation for the future study of laser spectral detection of ¹⁴CO₂.