Photolabile xenon hydrides: A case study of HXeSH and HXeH

Abstract

The photo-induced transformations of HXeSH and HXeH under the action of IR and visible light have been studied using FTIR spectroscopy. The xenon hydrides were produced by the X-ray induced decomposition of H2S and its isotopomers in a solid xenon matrix at 7.5 K followed by thermal annealing at the temperatures up to 45 K. Selective IR-induced photodissociation of HXeSH at 3500-2500 cm(-1) was attributed to vibrational excitation of the 3ν(H-Xe) mode. The IR-photodecomposed HXeSH molecules can be almost quantitative recovered below 22 K with very small effective activation energy (~20 meV) indicating local character of this process. Analysis of the photoactivity of xenon hydrides in the visible region revealed previously unknown absorptions for HXeSH (in the region of 400-700 nm) and HXeH (above 700 nm). The decomposition of HXeH occurs due to both direct photolysis and reactions of "hot" H atoms produced from the photodissociation of HXeSH. The efficiency of thermal recovery for both xenon hydrides after photolysis with visible light was found to be dependent on the excitation wavelength, which was explained by the effect of photon energy on spatial distribution of the dissociation fragments.

Matrix-Isolation Studies on the Radiation-Induced Chemistry in H2O/CO2 Systems: Reactions of Oxygen Atoms and Formation of HOCO Radical

“…A qualitatively similar behavior was observed for recombination of close H···SH pairs in solid xenon observed in our previous work. 28 The origin of this low barrier is presumably associated with local matrix relaxation. However, quantitative data cannot be extracted from the available experimental data.…”

Radiation-induced transformations of matrix-isolated formic acid: evidence for the HCOOH → HOCO + H channel

“…Our experimental approach of radiation-chemical experiments in solid noble gas (Ng) matrices doped with guest molecules has been generally described elsewhere. 34,[40][41][42][43][44] Formic acid vapours were mixed with an excess amount of an appropriate noble gas in a glass vacuum line following a standard manometric technique. Xe (99.9996%), Kr (99.99%), Ar (99.998%) and Ne (99.996%) were used as received for the preparation of the mixtures with the typical HCOOH to Ng ratio of 1 : 1000 (the ratio of 1 : 2500 was used in the case of a HCOOH/Ne sample).…”

Kinetics and mechanism of the radiation-chemical synthesis of krypton hydrides in solid krypton matrices

“…According to recent studies (Ryazantsev et al, 2013), an effective activation energy for "local" processes can be, at least, five times lower than that for "global" mobility. We believe that similar situation may occur in krypton.…”

“…In most cases, the noble gas hydrides were obtained using UV photolysis for dissociation of the precursor molecules. Only a few xenon hydrides were prepared by radiolysis Sukhov, 1996, Feldman et al, 2003;Feldman et al, 2005, Ryazantsev et al, 2013 and up to now this method was not used for obtaining krypton hydrides. The main difference between photolysis and radiolysis results from different mechanism of radiation effect on the isolated precursor molecules.…”