Theoretical investigations of atmospheric species relevant for the search of high-energy density materials

The great effort put in the last decades in the study of the natural cycles of ozone and carbon dioxide, of the chemistry of air pollution and its effect on the depletion of ozone and on the greenhouse effect caused by combustion processes has shown the great importance of simple, but very reactive, species, as ions, radicals and “exotic” molecules. Being these species in the gas phase, it is particularly appropriate for their study the joint use of theoretical methods, at ab initio level, with experimental techniques, mass spectrometry specifically. Both these investigations methods improved in the last few years and, for this reason, they are particularly suitable for applications involving the study of the atmosphere. On the one hand, the high performance computing allows nowadays the theoretical investigation of more and more complex species at a great level of accuracy. On the other hand, mass spectrometry, with the development of techniques of neutralization/reionization, can now study neutral species (radicals, unstable molecules) which are of great interest in the atmospheric chemistry. The combined use of accurate theoretical methods and mass spectrometry techniques allowed us to discover recently several new species, both cationic and neutral, which can be important for the chemistry of terrestrial and planetary atmospheres. The neutral species are experimentally detected starting from a charged precursor of appropriate connectivity for the neutralization experiment aimed at the formation of the neutral by a vertical process. Some of these new species show also the peculiarity of being metastable: these species can dissociate towards the products through very exothermic processes; however, the dissociation usually presents an activation barrier. This “metastability” suggests that these species should be promising candidates of high energy density materials (HEDM), which can be the next generation of environmentally benign propellants and explosives, especially in relation to spacecraft propulsion.