Ultra-Sensitive Multi-Gas Detection (CS₂/SO₂/H₂S/OCS) Using Spectral Reconstruction Combined with Differential Temperature Conversion

This study presents a detection system for the simultaneous quantification of SF₆ decomposition products (CS₂, SO₂, H₂S, and OCS) at ppb/ppm-level precision. To address the challenges of overlapping UV absorption spectra between CS₂ and SO₂, as well as the weak absorption characteristics of H₂S 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 CS₂ and SO₂ in the 194-225 nm range, enabling accurate concentration inversion. Subsequently, differential temperature conversion transforms CS₂, H₂S, and OCS into SO₂, leveraging the high sensitivity of UV-DOAS to SO₂. The distinct conversion rates of these sulfides at varying temperatures allow indirect determination of H₂S and OCS concentrations. Validation experiments confirm the system's effectiveness in SF₆ 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 SF₆ decomposition products in power equipment and environmental sulfide pollutants.