ИСТИНА

Direct study of highly reactive intermediates is the key to understanding the basic mechanisms of radiation-induced chemical reactions. Matrix isolation technique combined with IR and EPR spectroscopy at ultra low temperatures provides wide opportunities in this field. In particular, using this method one can easily generate and stabilize atomic hydrogen, characterize its dynamics and chemical reactions. Recent studies revealed an unusual class of hydrogen reactions under these conditions yielding noble-gas hydrides HNgY (where Ng is a rare gas atom and Y is an electronegative fragment). This is a kind of high-energy compounds with unusual chemical bonds. The investigations of the mechanism of formation and decomposition of such molecules provide important information about the nature of a chemical bond, dynamics of atoms and radicals in rare-gas matrices and kinetics of chemical reactions at low temperatures. In our laboratory, we have used X-ray irradiation of various precursors in a noble-gas matrix to obtain atomic hydrogen. Controlled annealing induced various chemical reactions, including generation of noble-gas hydrides. In this work we summarize the results of our recent studies on trapping and reactions of atomic hydrogen isolated in solid noble-gas matrices. These experiments revealed “local” and “global” reactions occurring at different temperatures. We have made an attempt to build a suitable kinetic model based on the studies of reactions producing different noble-gas hydrides (HKrCCH, HKrCl, HXeSH, HXeH). The possibility of controlling the scale of these processes by optical bleaching was demonstrated with the example of HXeSH and HXeH. Using mild IR photolysis, it was possible to selectively produce close radical pairs from this species, which recover at very low temperatures. The isotopic effects are discussed. Also, the attempts of synthesis of new noble-gas containing compounds are presented.