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As with all highly energetic substances, explosives are not perfectly stable – their safety and functional features change during ageing. The extent of chemical instability strongly depends on the chemical structure of the explosive – aromatic and aliphatic nitro compounds, secondary nitramines, and organic azides are relatively stable, whereas aliphatic nitrate esters suffer from much lower stability. The rate of ageing of an explosive can be strongly accelerated by incompatibility reactions between the explosive and contact materials. Stability and compatibility of explosives can be investigated with numerous test methods. A classification of these test methods based on test design and type of investigated ageing phenomenon is suggested in this paper. Furthermore, the most important test methods are discussed regarding applicability, advantages, drawbacks, and pitfalls.

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New two-dimensional correlation techniques in the field of pulsed microwave Fourier transform spectroscopy are presented. Five different pulse sequences were used to demonstrate connections between rotational transitions with well separated or with closely spaced frequencies. The introduction of two- and four-step phase cycles to select the desired coherence transfer pathways simplified the two-dimensional spectra considerably. Experiments were performed on methyl formate, norbornadiene, 1-chloro-1-fluoroethene, and vinyl cyanide. A theoretical treatment is given in terms of the density matrix formalism. The relationship between our experiments and similar nuclear magnetic resonance (NMR) techniques is also discussed.

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