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

Kameneva, Svetlana V.; Kobzarenko, Alexey V.; Feldman, Vladimir I.

doi:10.1016/j.radphyschem.2015.01.007

Cited by 15 publications

(6 citation statements)

References 33 publications

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“…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).…”

Section: Methodsmentioning

confidence: 99%

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

Ryazantsev

Feldman

2015

Phys. Chem. Chem. Phys.

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The effect of X-ray irradiation on the isolated formic acid molecules (HCOOH) in solid noble gas matrices (Xe, Kr, Ar, and Ne) at very low temperatures (6 K) was first studied by FTIR spectroscopy. Carbon oxides (CO and CO2) and hydrocarboxyl radicals (HOCO) have been detected as the principal degradation products. The formation of HOCO radicals represents a primary dissociation channel for formic acid, which was not reported previously under UV photolysis in solids. This reaction can be explained by the involvement of the recombination-induced excited states, which are not populated in photolysis. The effects of the matrix and the absorbed dose on the product formation were studied in detail and possible mechanisms are discussed with particular attention to the difference between radiolysis and UV-photolysis of the matrix-isolated formic acid. The results obtained provide a new insight into the effects of high-energy impact on the simplest carboxylic acid with possible implications to the astrochemical problems, in particular, the prebiotic evolution in the interstellar medium.

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Section: Methodsmentioning

confidence: 99%

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

Ryazantsev

Feldman

2015

Phys. Chem. Chem. Phys.

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“…Most recently Kameneva et al . studied in details the mechanism and kinetics of the processes leading to the formation of H-Kr-C=C-H in solid krypton matrices 9 . To date, a number of other krypton species have been identified, including van der Waals complexes 10 , numerous salts containing in particular KrF + and Kr 2 F 3 + cations 11 12 and several complexes containing coordinated neutral F-Kr-F units 13 14 .…”

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Krypton oxides under pressure

Zaleski‐Ejgierd

Lata

2016

Sci Rep

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Under high pressure, krypton, one of the most inert elements is predicted to become sufficiently reactive to form a new class of krypton compounds; krypton oxides. Using modern ab-initio evolutionary algorithms in combination with Density Functional Theory, we predict the existence of several thermodynamically stable Kr/O species at elevated pressures. In particular, our calculations indicate that at approx. 300 GPa the monoxide, KrO, should form spontaneously and remain thermo- and dynamically stable with respect to constituent elements and higher oxides. The monoxide is predicted to form non-molecular crystals with short Kr-O contacts, typical for genuine chemical bonds.

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“…Similar effect was observed in our recent studies of the X-ray induced degradation of HCOOH and HCN in different solid noble gas matrixes. , However, if we compare the efficiency in the terms of radiation-chemical yields (amount of decomposed CFCl 3 per unit of absorbed energy of X-ray radiation), it is clear that the degradation yields in neon and argon are considerably higher than those in heavier media. Nevertheless, it is worth noting that the accurate estimation of absorbed dose in krypton and xenon is rather difficult because of nonuniform dose distribution in these matrixes, even in the thin layers (this issue is discussed in more detail elsewhere). For this reason, we will use the degree of decomposition (conversion) of parent molecules as an invariant coordinate for comparison of the relative efficiency of the degradation channels in various noble gas matrixes.…”

Section: Resultsmentioning

confidence: 99%

Mechanisms of Radiation-Induced Degradation of CFCl₃ and CF₂Cl₂ in Noble-Gas Matrixes: An Evidence for “Hot” Ionic Channels in the Solid Phase

2016

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The X-ray-induced transformations of simple chlorofluorocarbons (CFCl and CFCl) in solid noble-gas matrixes (Ne, Ar, Kr, and Xe) at 7 K were studied in order to elucidate basic mechanisms of the radiation-chemical degradation with possible implications for stratospheric and extraterrestrial ice chemistry. The decomposition of parent molecules and formation of products were monitored by FTIR spectroscopy, and the identification was supported by ab initio calculations at the CCSD(T) level. It was shown that the ionic reaction channels were predominating in most cases (except for CFCl/Xe system). The primary radical cations (CFCl and CFCl) are either stabilized in matrixes or undergo fragmentation to yield the corresponding secondary cations (CFCl, CCl, CFCl) and halogen atoms. The probability of fragmentation through different channels demonstrates a remarkable matrix dependence, which was explained by the effect of excess energy resulting from the exothermic positive hole transfer from matrix atoms to freon molecules. A qualitative correlation between "hot" ionic fragmentation at low temperatures and gas-phase ion energetics was found. However, dissociative electron attachment leads to formation of neutral radicals (CFCl or CFCl) and chloride anions. One more possible way of dissociative electron attachment in the case of CFCl is formation of CF and Cl. A general scheme of the radiation-induced processes is proposed.

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

Cited by 15 publications

References 33 publications

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

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

Krypton oxides under pressure

Mechanisms of Radiation-Induced Degradation of CFCl₃ and CF₂Cl₂ in Noble-Gas Matrixes: An Evidence for “Hot” Ionic Channels in the Solid Phase

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

Cited by 15 publications

References 33 publications

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

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

Krypton oxides under pressure

Mechanisms of Radiation-Induced Degradation of CFCl3 and CF2Cl2 in Noble-Gas Matrixes: An Evidence for “Hot” Ionic Channels in the Solid Phase

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Mechanisms of Radiation-Induced Degradation of CFCl₃ and CF₂Cl₂ in Noble-Gas Matrixes: An Evidence for “Hot” Ionic Channels in the Solid Phase