A shock tube study on the thermal decomposition of CS₂ based on S(³P) and S(¹D) concentration measurements

Abstract

The thermal decomposition of CS₂ highly diluted in Ar was studied behind reflected shock waves by monitoring time-dependent absorption profiles of S(³P) and S(¹D) using atomic resonance absorption spectroscopy (ARAS). The rate coefficient of the reaction:

$$\begin{gathered} CS_2 + M\mathop \to \limits^{k_1 } CS + S + M, \hfill \\ k_1 = 5.1 \times 10^{14} \exp \left( {\frac{{ - 38150K}}{T}} \right)cm^3 mol^{ - 1} s^{ - 1} \hfill \\ \end{gathered} $$

((R1))

. was determined in experiments with initial concentrations of CS₂ between 5 and 50 ppm at post-shock conditions of 2300 K≤T≤3360 K and total densities between 2.2×10¹⁸ cm⁻³ and 3.9×10¹⁸ cm⁻³. In experiments with higher initial concentrations of 100 ppm CS₂ in Ar, the S(³P) concentrations were found to reach quasi-stationary values. From the steady state assumption a value for the rate coefficient of the most probable S consuming reaction:

$$\begin{gathered} CS_2 + S\mathop \rightleftharpoons \limits^{k_2 } CS + S_2 , \hfill \\ k_2 \approx 1.2 \times 10^{13} cm^3 mol^{ - 1} s^{ - 1} \hfill \\ \end{gathered} $$

((R2))

. was estimated at temperatures between 2100 K and 2340 K.