ИСТИНА

The discovery of noble gas hydrides of general type HNgY (Ng – noble-gas atom and Y – an electronegative fragment) was an important milestone of the modern low-temperature chemistry. In addition to general chemical interest, the studies of formation and dissociation of these unusual molecules may provide better understanding of dynamics of guest atoms in noble-gas matrices and development of new principles of manipulating chemical reactions at low temperatures using IR and visible light. In this work we studied the decomposition of H(D)XeSH, H(D)XeH molecules and H(D)XeO• radical under the action of visible and IR-light. All the xenon hydrides were prepared by the radiation-chemical method using various precursors. The isotopically selective mid-IR photodissociation (at 3500-2500cm-1) found for HXeSH was attributed to pumping of the 3νH-Xe stretching mode. This process had a truly local nature and the barrier for the thermally induced recovery is quite low (Ea ~15 meV, an order of magnitude smaller than that for global diffusion of H-atoms in Xe). The photoactivity in the near IR region (880-2400nm) was not detected for any mentioned xenon hydride. Meanwhile, H(D)XeSH was also found to decompose under visible light (400 – 700 nm) yielding a more diffuse spatial distribution of H atoms, as demonstrated by a “color-dependent” thermally induced recovery. This behavior was attributed to the excitation of an electronic transition. In the case of HXeH, analysis of the action spectrum revealed previously unknown electronic absorption in the red region. Photolysis with green light caused decomposition of the HXeO• radical, whereas its recovery was determined by the mobility of both O and H atoms.