Mechanism of chemical decomposition in a shocked condensed explosive

Abstract

A detailed understanding of shock induced chemical decomposition in explosives at the molecular level remains an outstanding problem. Time resolved optical spectroscopic techniques were used in our laboratory to address this problem. Nitromethane (NM), an insensitive high explosive, was investigated in this work as a model material. In particular, our emphasis was on understanding the chemical mechanism governing amine sensitization of shocked NM. The previously suggested reaction mechanisms are summarized briefly. We acquired the necessary data using optical absorption, fluorescence, and emission spectroscopies. Spectra of neat NM and mixtures of NM with amines shocked to within 12–17 GPa using step-wise loading were obtained. A transient intermediate was detected in sensitized NM with the optical absorption and fluorescence techniques. In a series of experiments with various amines, the intermediate was identified as a radical anion of NM. Several possible radical anion mechanisms were considered and evaluated. The base catalysis by amines is favored as the most plausible mechanism.