Chemical Transformation of Octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) Induced by Low Energy Electron Beam Irradiation

The effects of 8.0x10(-17) J (500 eV) and 3.2x10(-19) J (2 eV) electrons on chemical structure of octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) were studied in situ, under ultra-high vacuum conditions using a combination of X-ray photoelectron spectroscopy (XPS) and quadrupole mass spectrometry. XPS data indicated that electrons impact by 8.0x10(-17) J for 30 s caused a decrease in nitro group concentration, and a little shift in the binding energy of the nitrogen 1s peak. Such a phenomenon was found at very low kinetic energy (3.2x10(-19) J) with time evolution. Quadrupole mass spectrometry detected gas desorption after electron irradiation included H2O and H-2 mostly. Microscopy-IR spectroscopic investigations also proved that the intensity of nitro groups of HMX after irradiation decreased compared with those of the pristine HMX. We attributed the structure changes obtained by XPS and IR spectroscopy result in a chemical transformation, which was associated with low-energy dissociative electron attachment (DEA) of surface contaminants followed by deoxidization reactions to form the product molecules.