Ultra-Sensitive Multi-Gas Detection (CS<sub>2</sub>/SO<sub>2</sub>/H<sub>2</sub>S/OCS) Using Spectral Reconstruction Combined with Differential Temperature Conversion
Yongqi Wu, Fu Wan, Mu Li, Rui Zhu, Jie Gao, Lei Zhu, Weiping Kong, Yungang Zhang
Abstract
This study presents a detection system for the simultaneous quantification of SF 6 decomposition products (CS 2, SO 2, H 2 S, and OCS) at ppb/ppm-level precision. To address the challenges of overlapping UV absorption spectra between CS 2 and SO 2, as well as the weak absorption characteristics of H 2 S and OCS, the system combines ultraviolet differential optical absorption spectroscopy (UV-DOAS) with thermal conversion. At room temperature, spectral reconstruction effectively addresses the overlapping spectral features of CS 2 and SO 2 in the 194−225 nm range, enabling accurate concentration inversion. Subsequently, differential temperature conversion transforms CS 2, H 2 S, and OCS into SO 2, leveraging the high sensitivity of UV-DOAS to SO 2 . The distinct conversion rates of these sulfides at varying temperatures allow indirect determination of H 2 S and OCS concentrations. Validation experiments confirm the system’s effectiveness in SF 6 backgrounds. Four types of sulfides were detected at three different temperatures: room temperature, 800 K, and 1100 K, achieving a relative deviation of less than 5.78% in multicomponent detection. This approach overcomes the limitations of conventional spectroscopic techniques in resolving weak or overlapping absorption bands, offering a novel strategy for high-sensitivity monitoring of SF 6 decomposition products in power equipment and environmental sulfide pollutants.