Photogeneration of atomic hydrogen in rare gas matrices

Eloranta, Jussi; Vaskonen, Kari; Kunttu, Henrik

doi:10.1063/1.478697

Cited by 24 publications

(17 citation statements)

References 42 publications

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“…The accumulation efficiency in dilute Ne:H 2 mixtures decreased at higher H 2 concentrations which might be related to a higher recombination rate of H atoms in large clusters of pure H 2 . Similar behavior was observed for photolysis of HBr in solid Ar, where the HBr dissociation efficiency estimated from the atomic hydrogen yield increased from 18% for a 1:500 matrix to 100% in a 1:8000 matrix [43].…”

Section: Discussionsupporting

confidence: 75%

Electron spin resonance study of atomic hydrogen stabilized in solid neon below 1 K

et al. 2018

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We report on an electron spin resonance study of atomic hydrogen stabilized in a solid Ne matrices carried out at a high field of 4.6 T and temperatures below 1 K. The films of Ne, slowly deposited on the substrate at the temperature ∼1 K, exhibited a high degree of porosity. We found that H atoms may be trapped in two different substitutional positions in the Ne lattice as well as inside clusters of pure molecular H2 in the pores of the Ne film. The latter type of atoms was very unstable against recombination at temperatures 0.3-0.6 K. Based on the observed nearly instant decays after rapid small increase of temperature, we evaluate the lower limit of the recombination rate constant kr ≥ 5 · 10 −20 cm 3 s −1 at 0.6 K, five orders of magnitude larger than that previously found in the thin films of pure H2 at the same temperature. Such behavior assumes a very high mobility of atoms and may indicate a solid-to-liquid transition for H2 clusters of certain sizes, similar to that observed in experiments with H2 clusters inside helium droplets (Phys. Rev. Lett 101, 205301 (2008)). We found that the efficiency of dissociation of H2 in neon films is enhanced by 2 orders of magnitude compared to that in pure H2, which is instigated by a strong emission of secondary electrons.

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Section: Discussionsupporting

confidence: 75%

Electron spin resonance study of atomic hydrogen stabilized in solid neon below 1 K

et al. 2018

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“…As shown in our previous report, 19 the strong isotropic EPR signal of the hydrogen atom provides a versatile probe for photodissociation of hydrogen-containing molecules. Moreover, the hyperfine coupling constant is sensitive to the matrix environment and, consequently, allows detailed analysis of trapping site structures.…”

Section: Infrared Observationsmentioning

confidence: 96%

Photodissociation of Formaldehyde in Rare Gas (Xe, Kr, Ar, and Ne) Matrixes

Vaskonen

Kunttu

2003

J. Phys. Chem. A

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Infrared (IR) spectroscopy and electron paramagnetic resonance (EPR) are combined to study photodissociation of formaldehyde at photolysis wavelengths 308, 248, and 193 nm in rare gas matrixes. The photodissociation cross sections derived from the IR data show strong dependence on the matrix host and photolysis wavelength. Dissociation efficiency in Xe is 1-2 orders of magnitude higher than that in other matrixes. The kinetics of formation of atomic hydrogen and the final H atom concentration in the fully photolyzed sample vary significantly in different matrixes. In the 248 nm photolysis, the final number of H atoms in Kr and Ar matrixes is only 1 / 20 and 1 / 40 of the Xe matrix number, respectively. This behavior is discussed in the frame of a simple kinetic model. The anomalously fast dissociation at 193 nm in Xe matrix is discussed.

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“…This structure was detected in the pioneering work of Foner et al [48] and reproduced in many other studies, independent of the generation method (photolysis or radiolysis) [8,9,23,[49][50][51]. However, analysis of the structure pattern consisting of large number of anisotropic components in natural xenon was found to be quite complicated, so the trapping site nature for H atoms in solid xenon remained under discussion for a long time [49,50,53,54]. Using monoisotopic and isotopically doped xenon matrices, we have obtained conclusive evidence that more than 99% of radiolytically produced H atoms are trapped in nearly undistorted the octahedral (O h ) sites and only a very minor fraction occupies substitutional sites in the fcc xenon lattice [36].…”

Section: Production Distribution and Reactions Of Hydrogen Atomsmentioning

confidence: 98%

The radiation-induced chemistry in solid xenon matrices

Feldman

Kobzarenko

Orlov

et al. 2012

Low Temperature Physics

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The paper presents an overview of recent studies on the radiation-chemical transformations of guest molecules in solid xenon induced by fast electrons and x-ray irradiation. Specific features of the experimental approach based on combination of matrix isolation IR and EPR spectroscopy are briefly outlined (with particular impact on using monoisotopic and isotopically enriched xenon matrices). The results reveal rich and diverse radiation-induced chemistry in solid xenon, which is considered in the following major aspects: (1) matrix-induced and matrix assisted transformations of the primary guest radical cations; (2) production and dynamics of hydrogen atoms; (3) formation of xenon hydrides. Finally, preliminary results on the radiation-induced generation of oxygen atoms and ions in solid xenon are presented.

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Photogeneration of atomic hydrogen in rare gas matrices

Cited by 24 publications

References 42 publications

Electron spin resonance study of atomic hydrogen stabilized in solid neon below 1 K

Electron spin resonance study of atomic hydrogen stabilized in solid neon below 1 K

Photodissociation of Formaldehyde in Rare Gas (Xe, Kr, Ar, and Ne) Matrixes

The radiation-induced chemistry in solid xenon matrices

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