Nonequilibrium excitation of C-2 radicals during the thermal decompositionof C3O2 behind shock waves

C-2 concentrations and populations of the ground and the first excited vibr ational levels of electronically excited C-2(d(3)Pi) radicals during the th ermal decomposition of C3O2 behind shock waves were monitored by emission a nd absorption measurements in the (0-0) and the (1-0) Swan-bands. Experimen ts were carried out in mixtures of 1% C3O2 + Ar and 1% C3O2 + He at T = 210 0-3200 K and p =1.5-7.5 bar. In the whole range of conditions studied an es sential nonequlilibrium of electronic and vibrational states of nascent C-2 radicals was observed. For analyzing possible formation and consumption re actions of the excited C-2 radicals, a convenient kinetic scheme of the C3O 2 decomposition was developed, which considers both the recombinative pumpi ng process and exchange and quenching reactions of the C-2(d(3)Pi, v = 0, 1 ) states.