Insight into the Chemistry of PETN Under Shock Compression Through Ultrafast Broadband Mid-Infrared Absorption...

Area of Science:

• Shock physics
• Chemical kinetics
• Materials science

Background:

• Pentaerythritol tetranitrate (PETN) is a high explosive.
• Understanding shock-induced chemical reactions in energetic materials is crucial for safety and performance.

Purpose of the Study:

• To investigate the shock-induced chemistry of PETN using advanced spectroscopic techniques.
• To correlate experimental observations with molecular dynamics simulations.

Main Methods:

• Laser-driven shock compression of PETN thin films.
• Visible white light (VIS) and mid-infrared (MIR) transient absorption spectroscopy.
• Reactive molecular dynamics simulations.

Main Results:

• Irreversible chemistry observed in PETN above 30 GPa shock pressure.
• Increased absorption at the antisymmetric NO2 stretch, but not symmetric NO2 stretch.
• Appearance of broad absorption near 2200 cm-1, consistent with C≡O or N2O formation.
• Simulations align with experiments up to 30 GPa, highlighting NO and NO2 contributions.

Conclusions:

• Shock compression above 30 GPa initiates significant chemical changes in PETN.
• Initial reaction steps likely involve C≡O or N2O bond formation and nitrite formation.
• Absence of significant hydroxyl or amine concentrations in early reaction stages.