Photothermal Initiation of Hybrid Organic/Inorganic Metastable Interstitial Composites: Synergistic Effects on the Dynamics of Energy Release

The organic high-energy material pentaerythritol tetranitrate (PETN) was incorporated at low concentrations into Al (100 nm)/Fe2O3 metastable intersitital composites (MIC) to form a hybrid organ ichnorganic high-energy material. Studies of the dynamics of energy release were carried out by initiating the reaction photothermally with a single 8 ns pulse of the 1064 nm fundamental of a Nd:YAG laser. The reaction dynamics were measured using time-resolved spectroscopy of the light emitted from the deflagrating material. Two parameters were measured: the time to initiation and the duration of the deflagration. The presence of small amounts of PETN (16 mg/g of MIC) results in a dramatic decrease in the initiation time. This is attributed to a contribution to the temperature of the reacting system from the combustion of the PETN that, at lower loadings, appears to follow an Arrhenius dependence. The presence of PETN was also found to reduce the energy density required for single-pulse photothermal initiation by an order of magnitude, suggesting that hybrid materials such as this may be engineered to optimize their use as an efficient photodetonation medium.