Metastable Dissociation of Anions Formed by Electron Attachment

Abstract

A comprehensive analysis of metastable dissociation of 2,4-dinitrotoluene (DNT) parent anions formed by attachment of electrons of controlled energy is presented. We characterize the energy dependence and kinetic energy release of the reaction which competes with autodetachment. A surprising finding is a highly exothermic metastable reaction triggered by the attachment of thermal electrons which we relate to the well-known electrostatic ignition hazards of DNT and other explosives. Quantum chemical calculations are performed for dinitrobenzene in order to elucidate the process of NO abstraction.

Probing di-nitrobenzene by low energy electrons

“…A remarkable exception is electron attachment to C 60 (and other fullerenes) generating metastable parent anions up to electron energies of 10 eV [32]. We again note that very recent experiments on di-nitrotoluene [20] revealed that low energy electron attachment leads to both prompt DEA and a metastable decomposition of the transient anion.…”

“…It was recently demonstrated [18] by measuring the NO 2 − resonance energies for a series of nitro aromatic compounds including isomers that it is possible to distinguish between the different compounds. DNT has recently been studied by the combined use of a time-of-flight mass spectrometer and two sector field magnetic mass spectrometer [20]. It is found that the transient negative ion formed upon electron attachment promptly decomposes by the loss of neutral H 2 O, N 2 O and further fragments.…”

Dissociative Electron Attachment to the Nitroamine HMX (Octahydro-1,3,5,7-Tetranitro-1,3,5,7-Tetrazocine)

“…22) lending evidence to their more explosive character when compared to other explosives such as TNT 20 and the other nitrocompounds. [16][17][18][19]23,24,26 In Figure 3 we show the fully optimized geometry obtained at MP2/6-311++G(2d,p)…”

Metastable anions of dinitrobenzene: Resonances for electron attachment and kinetic energy release

“…This value is even larger than the KER found for metastable loss of NO from 2,4-dinitrotoluene after lowenergy electron attachment, which was 0.7 eV. 9 The MIKE peak in Fig. 8(c) corresponds to a much narrower MaxwellBoltzmann-type KER distribution; the average KER is only 0.13 eV.…”

“…[6][7][8] Some of the fragments of DNB anions feature larger electron affinities which, combined with the low thermochemical stability of neutral DNB, implies that attachment of lowenergy electrons to DNB may trigger dissociative reactions that are accompanied by large kinetic energy release (KER), similar to a recently described highly exothermic reaction for electron attachment to 2,4-dinitrotoluene. 9 Interestingly, these reactions may occur in the metastable time window, i.e., microseconds after electron attachment. Bowie et al 10 have reported kinetic energy release values of 0.5-1.0 eV for the metastable reaction DNB + e → DNB * − → (DNB-NO) − + NO,…”