Ionisation energy, electron affinity, and mass spectral decomposition mechanisms of RDX isomers upon electron attachment and electron ionisation

The structures, ionisation energies (IE), and electron affinities (EA) of 1,3,5-trinitro-1,3,5-triazacyclohexane (RDX) isomers upon loss and gain of an electron were calculated using density functional theory (DFT) methods. The adiabatic electron affinities (EA(ad)) range from 1 to 2 eV. The vertical detachment energies are between 1.3 and 4.0 eV. The adiabatic ionisation energies (IEad) are in the 9.9-10.2 eV range. The vertical ionisation energies are in the 10.4-10.9 eV range. It is shown that NO2-/NO2 loss would be common in anions and cations, respectively. Isomerisation and N-N bond dissociation accompany cation and anion formation, respectively. The suggested mass spectral fragmentation products for the cations along the S-0 surface are 84, 130, and 176 amu, in agreement with earlier mass spectrometry studies. [GRAPHICS] .