A SHOCK TUBE-LASER FLASH-PHOTOLYSIS STUDY OF THE REACTION COS-REVERSIBLE-ARROW-CO+S2(S)

The reaction of S atoms with COS was studied behind reflected shock wa ves in the temperature range 1200 K less-than-or-equal-to T less-than- or-equal-to 1670 K at pressures between 0.6 and 2.0 bar. The S atoms w ere generated by UV laser flash photolysis of mixtures containing 50-2 00 ppm COS diluted in Ar and were monitored by atomic resonance absorp tion spectroscopy. From the decay of the S atom absorption signals the rate coefficient of the reaction COS + S half arrow right over half a rrow left CO + S2 (R2), k2 = 6.0 x 10(13) exp(-4560 K/T) cm3 mol-1 s-1 , was determined by assuming first-order kinetics. In addition, quasi- stationary S atom profiles obtained during the high-temperature pyroly sis of 100 ppm COS in Ar were analyzed. Based on a simplified kinetic model, the given k2 value was verified to be valid for temperatures up to T = 2180 K.