A laboratory study on the formation of nitrous oxide by the reaction N2(A3Σu+) + O2 → N2O + O

Atmospherically relevant ion chemistry of ozone and its cation

The importance of ionic processes that occur in terrestrial, planetary, and stellar atmospheres is receiving increasing recognition. Actually, ions play important, often crucial, roles in a variety of atmospheric processes throughout the universe, and a strong link with the neutral chemistry is also apparent. In the terrestrial atmosphere, the ionic reactions are most relevant in those transient and fleeting events, e.g., lightning, coronas (in thunderstorm clouds and along power lines), where the local ion density is much higher than in unperturbed air, and the chemical systems are typically far from equilibrium. In such cases, ozone, a key molecule for the terrestrial atmosphere, is also present in high local concentrations; it is formed from O(2) by the same transient event. Accordingly, this review provides a survey of the positive ion chemistry of ozone with several of the most important "atmospheric" species: the reactions, the products, and the importance of the examined processes are discussed also in the light of the local thermodynamic disequilibrium (LTD) approach to the chemistry of transient atmospheric events. In all such studies, mass spectrometry is traditionally, and remains today, the experimental technique of choice. The novel application of mass spectrometry to the study of neutral species (NRMS), highly successful for the preparation and positive detection of long-sought, otherwise inaccessible, short-lived neutrals, makes mass spectrometry the most powerful tool now available for the study of the species and processes that are relevant to atmospheric chemistry. Selected examples of the interlink between the neutral and the ionic chemistry are also illustrated.

In-target production of high specific radioactivity [15O]nitrous oxide by deuteron irradiation of nitrogen gas

A simple and rapid production method for high specific radioactivity [15O]N2O has been developed based on the 14N(d,n)15O reaction on high-purity nitrogen gas in a flow-through target irradiated with a 0.5 microA beam of 7 MeV deuterons. The [15O]N2O formed during irradiation is selectively concentrated from the target effluent by adsorption on a zeolite during 150 s and subsequently released by rapid heating into a pulse with a full width at half maximum of 3.5 s. The radioactivity and specific radioactivity in the pulse amount to 4 MBq [15O]N2O and 4.5 x 10(13) Bq/mol respectively with a radiochemical purity >99.95%. A tenfold higher specific radioactivity may be feasible at larger beam currents. It was shown that stable N2O was also formed during irradiation. Based on responses to variations in various parameters during irradiation and on analyses performed on the products, an explanation is given on the mechanisms of in-target [15O]N2O and N2O formation, involving reaction of a particular excited state of O3 with N2.