The synthesis, physical properties, and calculated performances of six stereo-and regioisomeric cyclobutane nitric ester materials are described. While the calculated performances of these isomers, as expected, were similar, their physical properties were found to be extremely different. By alteration of the stereo-and regiochemistry, complete tunability in the form of low-or high-melting solids, stand-alone melt-castable explosives, melt-castable explosive eutectic compounds, and liquid propellant materials was obtained. This demonstrates that theoretical calculations should not be the main factor in driving the design of new materials and that stereo-and regiochemistry matter in the design of compounds of potential relevance to energetic formulators.

Discussed herein is the synthesis of bis­(1,2,4-oxadiazole)­bis­(methylene) dinitrate, determination of its crystal structure by X-ray diffractometry, calculations of its explosive performance, and sensitivity measurements. Steps taken to optimize the synthesis process and to improve yields of the dinitrate are also discussed. Bis­(1,2,4-oxadiazole)­bis­(methylene) dinitrate has a calculated detonation pressure 50% higher than that of TNT. The dinitrate compound exhibits a relatively high decomposition temperature that is rarely observed for nitrate-based compounds. The dinitrate was found to have lower sensitivities to impact and friction compared with RDX. It is believed that intramolecular hydrogen bonding observed in the crystal lattice assists in the relatively high thermal stability and relatively low sensitivity of the material.

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A new method for detecting trace vapors of NO2-containing compounds near atmospheric conditions has been demonstrated with the use of one-color-laser photofragmentation/ionization spectrometry. An ArF laser is employed to both photolytically fragment the target molecules in a collision-free environment and ionize the characteristic NO fragments. The production of NO is hypothesized to result from a combination of two NO2 unimolecular fragmentation pathways, one yielding NO in its X2II electronic ground state and the other in its A2Σ+ excited state. Ionization of ground-state NO molecules is accomplished by resonance-enhanced multiphoton ionization processes via its A2Σ+ ← X2II (3, 0), B2II ← X2II (7, 0) and/or D2Σ+ ← X2II (0, 1) bands at 193 nm. The analytical utility of this method is demonstrated in a molecular beam time-of-flight apparatus. Limits of detection range from the parts-per-million (ppm) to parts-per-billion (ppb) level for NO, NO2, CH3NO2, dimethylnitramine (DMNA), ortho- and meta-nitrotoluene, nitrobenzene, and trinitrotoluene (TNT). Under effusive beam experimental conditions, discrimination between structural isomers, ortho-nitrotoluene and meta-nitrotoluene, has been demonstrated with the use of their characteristic photofragmentation/ionization mass spectra.

The development of a novel technique for sensing trace vapors of NOr-containlng compounds Is reported. This technique Is based on the use of one laser operating at 226 nm to both photofragment the target molecule and detect the characteristic NO fragment, formed from a rapid predissociation of N02, by resonance-enhanced multiphoton Ionization (REMPI) and/or laser-induced fluorescence (LIF) via Its A* 12 32+-X2II (0,0) band origin. The analytical utility of this technique Is demonstrated on a number of compounds, Including dbnethylnltramlne, nltromethane, nitrobenzene, trinitrotoluene (TNT), and 1,3,5-trinltrohexahydro-1,3,5-triazlne (RDX), employing molecular beam sampling with tlme-of-fllght mass spectrometrlc analysis of the Jet-cooled analyte seeded In an atmosphere of buffer gas. With the present system, limits of detection of 8 and 24 parts per blWon (ppb) are obtained for RDX and TNT, respectively, using only ~100 pj/pulse of laser energy. The limits of detection of the other compounds studied are also presented and discussed.