Atom Formation Rates behind Shock Waves in Oxygen

Atomic absorption spectrophotometry has been used to monitor the rate of oxygen atom formation behind shock waves in oxygen–argon mixtures. These observations were made by observing the time history of absorption at the oxygen atom triplet near 1300 Å. The atomic absorption coefficients were determined experimentally in the shock tube. These observations lead to an oxygen–argon dissociation rate given by $k_{{\mathrm{O}}_2\mathrm{\hspace{0.17em}-\hspace{0.17em}Ar}}{\text{\hspace{0.17em}=\hspace{0.17em}1.85(±\hspace{0.17em}14\%)\hspace{0.17em}×\hspace{0.17em}10}}^{11}{T}^{\text{0.5}}\exp \text{(−\hspace{0.17em}95 700\hspace{0.17em}/\hspace{0.17em}RT)}{\mathrm{cm}}^3{\mathrm{mole}}^{\text{−1}}·{\sec }^{\text{−1}}$ over the temperature range 2850°–5550°K. In addition this technique is shown to provide a powerful method for examining the vibration–dissociation coupling region. Measurements of the induction time for a steady‐state atom formation rate to be established were obtained in the temperature range 2850°–5000°K. These measurements are compared with previously published experimental and theoretical induction times for dissociation in oxygen–argon mixtures.