The photochemistry of RDX in solid argon at 10 K

The photochemistry of RDX was studied in argon matrices at 10 K and examined by FTIR spectroscopy. The spectra and kinetics of product growth indicate that there are two decomposition pathways: [I] RDX → 4NO + 2CH2O + N2 + CH2 → 4NO + 2CO + N2 +CH4 + H2 [II] RDX → N2O + [O3 + N2] or [N2O3] + CO2 + C2H2 +N2 + 2H2 The mechanism II nitrogen products can easily be rationalized for the chair configuration of RDX with axial NO2 groups adjacent (Cs symmetry). When considering the carbon products of II, it may be necessary to postulate intermolecular reactions. Our studies gave no evidence for the symmetric triple fission path, which leads to N2O and CH2O, nor for the NO2 stripping mechanism reported for the gas-phase thermal reactions, which leads to the formation of NO2 and HCN. Rather, our findings were more consistent with the known condensed phase products. The production of CH4, C2H2, N2O3, and O3 are unique to the matrix study. Key words: RDX, photochemistry, argon matrices.