Shock Wave Induced Decomposition of RDX: Time-Resolved Spectroscopy

Abstract

Time-resolved optical spectroscopy was used to examine chemical decomposition of RDX crystals shocked along the [111] orientation to peak stresses between 7 and 20 GPa. Shock-induced emission, produced by decomposition intermediates, was observed over a broad spectral range from 350 to 850 nm. A threshold in the emission response of RDX was found at about 10 GPa peak stress. Below this threshold, the emission spectrum remained unchanged during shock compression. Above 10 GPa, the emission spectrum changed with a long wavelength component dominating the spectrum. The long wavelength emission is attributed to the formation of NO2 radicals. Above the 10 GPa threshold, the spectrally integrated intensity increased significantly, suggesting the acceleration of chemical decomposition. This acceleration is attributed to bimolecular reactions between unreacted RDX and free radicals. These results provide a significant experimental foundation for further development of a decomposition mechanism for shocked RDX (following paper in this issue).

The characteristics of laser‐driven shock wave investigated by time‐resolved Raman spectroscopy

“…In recent decades, there have been a number of reports on shock compression using ultrafast, timeresolved Raman spectroscopy. The influence of substituent groups to shock compression has been studied by Matsuda et al [10,11] using benzene and its derivatives; many experiments on shockinduced decomposition of energetic materials were carried out by Gupta et al [12] However, there are few investigations on the characteristics of the shock wave itself. The determination of these characteristics is useful for the research of shock phenomena involving the generation and the interaction with materials of shock waves.…”

Energetic materials under high pressures and temperatures: stability, polymorphism and decomposition of RDX

“…Therefore, to gain insight into the shock-induced decomposition the experiments were performed at higher stresses [11]. At stresses higher than7 GPa, we observed, in addition to changes in the Raman spectra, a gradual raise of light emission from the crystal with time.…”

“…Emission experiments were performed for stresses between 7 and 20 GPa. Details of shock experiments and detection techniques can be found elsewhere [10,11,13, and 14].…”

High spectral resolution, real-time, Raman spectroscopy in shock compression experiments

“…[14][15][16][17] To minimize this contribution, the intensified CCD was gated on for only 60 ns. Furthermore, the laser pulse was carefully synchronized with the gated detector; the gate time was positioned immediately after the sample reached peak stress, when the emission is generally lower.…”

“…Furthermore, time-resolved measurements are inefficient in rejecting the background light that often arises from shock compression of materials (e.g., Refs. [13][14][15][16][17].…”