ИСТИНА

HCN and related radicals are fundamentally important species, which play significant role in extraterrestrial and interstellar chemistry. Matrix isolation studies make it possible to simulate the behavior of these species in the radiation environment at low temperatures. Furthermore, the radiation-induced chemistry of HCN in solid noble gas matrices attracts specific interest due to possible formation of fascinating molecules of noble gas hydrides (HXeCN, HXeNC, and HKrCN) [1]. In the present work we report the results of experimental studies on the radiation-induced transformations of HCN in solid krypton by a combination of FTIR and EPR spectroscopy. The experimental approach and design were described previously [2]. The matrix deposited samples (HCN/Kr) were irradiated with X-rays (30 keV) at 7 K and annealed carefully at different temperatures between 7 and 50 K. Irradiation leads to decomposition of HCN yielding trapped hydrogen atoms and CN radicals detected by EPR. In addition, the IR spectra demonstrate some isomerization to give HNC radicals. Annealing the sample results in mobilization of trapped H atoms, which react with other trapped species resulting in formation of HKrCN molecules, H2CN and HCNH radicals identified by IR and EPR spectroscopy. Based on comparison of IR and EPR results, we may conclude that the formation of HKrCN is one of the main channels of the reactions of H atoms. Mechanism of formation and stability of HKrCN in solid krypton were investigated. All the radicals demonstrate temperature depending dynamics as found by EPR. The structure of radicals produced by hydrogen addition to HCN molecules (H2CN and HCNH) is discussed on the basis of spectroscopic data and quantum chemical calculations. References [1] M. Pettersson et al., J. Chem. Phys. 109, 618 (1998). [2] S.V. Ryazantsev et al., J. Chem. Phys. 139, 124315 (2013).