Study of the laser-induced decomposition of energetic materials at static high-pressure by time-resolved absorption spectroscopy

The reactivity of laser-initiated energetic materials has been studied at high-pressure using time-resolved absorption spectroscopy in a diamond anvil cell (DAC). The results obtained for nitromethane (NM) are presented in this paper. A change in reactivity is clearly seen around 25 GPa. Below this pressure, a one-step reaction is found to occur. The decomposition products formed behind the combustion front are essentially carbon residues as shown by Raman spectroscopy. At higher pressure, a two-step mechanism is observed. The first step, which is similar to the reaction observed below 25 GPa, leads to the formation of carbonaceous products. It is followed by a slower step which leads to the formation of a transparent amorphous product. This product remains stable in the DAC after reaction.