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A. Zoermer, H. Grothe, O. Galvez:
"Atmospherically Relevant Halogen Oxides Studied in Matrix Isolation Experiments";
Vortrag: Seminar der VERA Forschungsgruppe am Institut für Physik, Universität Wien, Wien (eingeladen); 29.11.2007.

Halogens and most of their covalent compounds are well known to be very aggressive substances. When the ozone hole was discovered in 1985, it was soon found out that halogen oxides, which are exotic species at first glance, are key players in the destruction cycles of stratospheric ozone. Also in the troposphere, especially in the marine boundary layer and in the vicinity of salt lakes, halogen compounds play a distinct role. The research on atmospheric reaction cycles and the protagonists therein is still far from being completed. Many of the halogen species which are formed from presursors such as chlorine fluorine carbons (CFCs), sea salt aerosols, or decomposed halogenated molecules released e.g. by marine algae, are merely predicted, but were neither detected in field measurements nor even in the laboratory.
To contribute to the still fragmentary data base on these aggressive species, matrix isolation experiments were performed. Mixtures of bromine and oxygen in a large amount of argon were reacted in a microwave discharge and immediately afterwards quenched at 6.5 K to preserve the elusive bromine species, mostly radicals, in an inert argon environment. This method yielded, beside molecules already known, new bromine oxides which were identified by infrared spectroscopy. Careful tempering, which in this case means warming to 32 K at most, resulted in controlled subsequent reactions inside the frozen gas layer, thus generating even more new molecules and also giving an insight into their reaction pathways.