CHEMICAL-REACTIONS AT DETONATION FRONTS IN SOLIDS

Detonation fronts propagate too fast for the chemical reactions that d rive them to be thermally activated. It is proposed that the compressi on in such fronts causes local metallization when either the density, or the bending of covalent bonds, reaches a critical level which can b e estimated from simple models. In the case of the density, this can b e estimated from the Herzfeld-Mott model; and in the case of bond-bend ing, from parabolic variation of the LUMO and HOMO molecular energy le vels. Adiabatic expansion of the delocalized electrons provides the hi gh pressure needed to accelerate the ions in the front. Specific examp les that are discussed are lead azide, ammonium ions, and nitrate ions . In addition it is argued that this approach is consistent with: obse rved critical compressions; detonation velocities; the resonance energ ies of chemical bonds, polarizabilities and the stabilities of energet ic materials. Metallization explains why hyper-fast reactions can occu r athermally, and propagate supersonically.