MULTIPLE ROLES OF HIGHLY VIBRATIONALLY EXCITED MOLECULES IN THE REACTION ZONES OF DETONATION-WAVES

Recent experimental and theoretical advances in the understanding of h igh-pressure, high-temperature chemical kinetics are used to extend th e nonequilibrium Zeldovich-von Neumann-Doring (NEZND) theory of self-s ustaining detonation in liquid and solid explosives. The attainment of vibrational equilibrium behind the leading shock front by multiphonon up-pumping and internal vibrational energy redistribution establishes a high-temperature, high-density transition state or series of transi tion states through which the chemical decomposition proceeds. The rea ction rate constants for the initial unimolecular decomposition steps are accurately calculated using high-temperature, high-density transit ion-state theory. These early reactions are endothermic or weakly exot hermic, but they channel most of the available energy into excited vib rational states of intermediate product species. The intermediate prod ucts transfer some of their vibrational energy back into the transitio n states, accelerating the overall reaction rates. As the decompositio n progresses, the highly vibrationally excited diatomic and triatomic molecules formed in very exothermic chain reactions are rapidly vibrat ionally equilibrated by ''supercollisions'', which transfer large amou nts of vibrational energy between these molecules. Along with vibratio nal -rotational and vibrational-translational energy transfer, these e xcited vibrational modes relax to thermal equilibrium by amplifying pr essure wavelets of certain frequencies. These wavelets then propagate to the leading shock front and reinforce it. This is the physical mech anism by which the leading shock front is sustained by the chemical en ergy release.