Absorption cross-section measurements of elevated temperature S2 in the 245–320 nm region based on UV-DOAS with thermal conversion

Due to the harsh environment in which S₂ exists, its spectral properties have rarely been investigated. This paper proposes a measurement method for determining the absorption cross-section (ACS) of S₂ at high temperatures. A high-temperature measurement device was designed based on the thermodynamic properties of S₂, and the absorption spectra of S₂ were measured at high temperature (1000–1150 K) under atmospheric pressure. To address the challenge of accurately quantifying trace concentrations of S₂, a conversion measurement method was proposed. In this method, O₂ was injected at high temperatures to convert S₂ into SO₂, allowing the concentration of S₂ to be indirectly determined by calculating the concentration of SO₂ before and after the conversion. Additionally, a spectral reconstruction filter was introduced in the calculation of the S₂ absorption spectrum to eliminate SO₂ interference. Ultimately, the S₂ ACS was obtained with a relative uncertainty of 5 %.