Published online by Cambridge University Press: 15 February 2011
The radiation stabilities of the nitramine explosives 1,4-dinitroglycolurile (DINGU), 1,4-dimethyl-2,5-dinitroglycolurile (DMD) and hexanitrohexaazaisowurtzitane (HNIW) have been determined using XPS. Samples were exposed to x-rays for times up to eight hours while photoelectron spectra were recorded in the carbon, oxygen, and nitrogen Is energy regions and mass spectra were recorded of gases evolved during the decomposition process. These data are compared to the previously determined stabilities for cyclotrimethylene trinitramine (RDX) and cyclotetramethylene tetranitramine (HlMX). The N1s spectra of the irradiated materials show the NO2 peak decreases relative to the total nitrogen signal while low binding energy peaks grow. The rate of loss of the NO2 peak was fit to first order kinetics and the rate constants obtained show some correlation with the N-N bond strength as measured by the average N-N bond distance and the average NO2 asymetric stretch frequency. Despite the differences in structure of these molecules (DINGU and DMD are bicyclic rings, RDX and HMX are rings and HNIW is a cage) the radiation stability appears to be controlled by the strength of the N-N bond.