Decomposition of pentaerythritol tetranitrate [C(CH2ONO2)4] following electronic excitation

We report the experimental and theoretical study of the decomposition of gas phase pentaerythritol tetranitrate (PETN) [C(CH2ONO2)4] following electronic state excitation. PETN has received major attention as an insensitive, high energy explosive; however, the mechanism and dynamics of the decomposition of this material are not clear yet. The initial decomposition mechanism of PETN is explored with nanosecond energy resolved spectroscopy and quantum chemical theory employing the ONIOM algorithm at the complete active space self-consistent field (CASSCF) level. The nitric oxide (NO) molecule is observed as an initial decomposition product from PETN at three UV excitation wavelengths (226, 236, and 248 nm) with a pulse duration of 8 ns. Energies of the three excitation wavelengths coincide with the (0–0), (0–1), and (0–2) vibronic bands of the NO A 2Σ+ ← X 2Π electronic transition, respectively. A unique excitation wavelength independent dissociation channel is observed for PETN, which generates the NO prod...