ИСТИНА

The HCN molecule and related radicals are important species in extraterrestrial chemistry occurring under high-energy irradiation. Using matrix isolation technique makes it possible to investigate in detail the spectroscopic properties, dynamics and reactivity of the intermediates produced from HCN kinds of irradiation at low temperatures. Furthermore, there is an additional aspect of interest to the radiolysis of HCN in solid krypton and xenon since hydrogen cyanide may serve as a precursor for unusual high-energy molecules of noble-gas hydrides, namely HKrCN, HXeCN and HXeNC [1]. In this work we report the results of systematic studies on the radiation-induced transformations of H(D)CN/Ng systems (Ng = Ne, Ar, Kr or Xe) using a combination of FTIR and EPR spectroscopy. The experimental approach and design was similar to that used in our previous work [2]. Deposited samples of H(D)CN/Ng were irradiated with X-rays (maximum energy 33 keV) at 7 K and annealed carefully at the temperatures between 7 to 70 K. It was shown that HCN is decomposed efficiently producing H and CN radicals and HNC isomer. The thermally induced reactions of H atoms in different matrices result in the formation of two isomeric radicals, H2CN and trans-HCNH, the former being predominated. The vibrational frequencies and magnetic resonance parameters of these species calculated at the DFT-PBE1/L2 and CCSD(T)/L2 levels are in reasonable agreement with the experimental results. In addition, HKrCN was found in the case of krypton, whereas HXeCN and HXeNC were produced in solid xenon. It was found that HCNH radical could be effectively bleached with visible light. The comparison of experimental and computational data made it possible to assign new vibrational band (previously unknown) to this radical. The reaction mechanisms and contribution of different channels are discussed on the basis of the results obtained. This work was supported by a grant from the Russian Science Foundation (project 14-13-01266).