SO₃ Concentration Measurement Using Ultraviolet Absorption Spectroscopy and Thermal Conversion

Abstract

Ultraviolet absorption spectroscopy was used to measure the absorption cross section of SO₃. The measured cross section had a peak value of about 9×10^-19 cm² near wavelength 200 nm. In addition, a method to measure the concentration of SO₃ by thermal conversion of SO₃ to SO₂ at elevated temperatures was developed. Laboratory experiments showed that SO₃ can be converted to SO₂ at temperatures of about 870K. These methods are potentially applicable to flue gas monitoring in fossil-burning power plants.