Shock Tube Measurements on the Thermal Decomposition of COS

Abstract

AbstractThe thermal decomposition of carbonyl sulfide was studied behind reflected shock waves by direct measurements of the time‐dependent S(3P) atom concentration using atomic resonance absorption spectroscopy (ARAS). The experiments were performed in highly diluted mixtures of Ar with relative concentrations of COS between 4 to 100 ppm in the temperature range 1750 K ≤ T ≤ 2990 K at pressures between 0.5 bar and 1.5 bar. In reaction systems with very low concentrations (4 – 30 ppm COS in Ar) the initial reaction magnified image was found to dominante the initial slope of the measured S(3P) atom concentration profiles. The rate coefficient obtained results in: magnified image In reaction systems with higher initial concentrations of 100 ppm COS the measured S(3P) atom concentration profiles were additionally affected by secondary reactions consuming sulfur atoms. The most probable reaction is magnified image which has an influence on S(3P) at later reaction times. A rate coefficient for reaction (R2) of magnified image was determined from the present experiments by fitting calculated S(3P) atom profiles to measured ones. The given mean value is to be valid for temperatures near 2000 K.