MEASUREMENT OF O(D-1) FORMATION DURING THERMAL-DECOMPOSITION OF CO2 BEHIND SHOCK-WAVES

Atomic Resonance Absorption Spectroscopy (ARAS) was applied to measure the time dependent concentration of electronically excited O(D-1)-ato ms during the thermal decomposition of CO2 behind reflected shock wave s. The experiments were performed in the temperature range 4102 K less than or equal to T < 6375 K at pressures 0.2 to 1.9 bar with initial gas mixtures of 100 to 1000 ppm CO2 diluted in Ar. The measured O(D-1) -formation rate at early reaction times divided by the initial reactan t concentrations was found to obey the Arrhenius law: d[O(D-1)]/dt/[CO 2](0)[Ar]/(t approximate to 0) = 1.23 x 10(14) exp (-74810 K/T) cm(3)m ol(-1)s(-1) The assumption of a fast thermalisation between the O(P-3) and O(D-1) states is in agreement with previous measurements of the O (3P) formation during the thermal decomposition of CO2, see Burmeister and Roth (1990).