Explosive desorption induced by radical–radical interaction in methane-doped Ar matrices

Savchenko, E. V.; Khyzhniy, I. V.; Uyutnov, S. A.; Bludov, M. A.; Bondybey, V. E.

doi:10.1016/j.nimb.2023.01.005

Cited by 3 publications

(2 citation statements)

References 38 publications

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“…Below, we briefly summarize the results of our previous studies of radiation effects induced by an electron beam in Ar matrices doped with CH 4 [53][54][55]59]. In the cathodoluminescence (CL) spectra, the following products of radiation-induced methane transformation were recorded: H, CH and C. It has been shown that because of the small penetration depth of electrons, the bulk of the matrix is excited preferentially by photons of the matrix with an energy of 9.8 eV (the most intense emission band of the self-trapped excitons); in other words, "internal photolysis" occurs.…”

Section: Introductionmentioning

confidence: 99%

“…Long-term and short-term oscillations of the total particle yields were found and interpreted as thermo-concentration self-oscillations, similar to those considered in [44] for the case of pure methane. It has been shown that they can be initiated either by the spontaneous release of stored energy upon reaching a critical concentration of reactants, or by external heating of the doped matrix to stimulate diffusion and release the stored chemical energy in subsequent recombination reactions [59]. Preliminary measurements of the dose dependence of the optical emission of the H atom carried out on a lightly doped Ar matrix (C = 1%) at LHe temperature found a puzzling fact-an increase in this emission with a pressure burst [54].…”

Section: Introductionmentioning

confidence: 99%

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Matrix-Assisted Processes in CH4-Doped Ar Ices Irradiated with an Electron Beam

Bludov,

Khyzhniy,

Uyutnov

et al. 2023

Methane

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The relaxation processes induced by exposure of the Ar matrices doped with CH4 (0.1–10%) to an electron beam were studied with a focus on the dynamics of radiolysis products—H atoms, H2 molecules, CH radicals, and energy transfer processes. Three channels of energy transfer to dopant and radiolysis products were discussed, including free charge carriers, free excitons and photons from the “intrinsic source” provided by the emission of the self-trapped excitons. Radiolysis products along with the total yield of desorbing particles were monitored in a correlated manner. Analysis of methane transformation reactions induced by free excitons showed that the CH radical can be considered a marker of the CH3 species. The competition between exciton self-trapping and energy transfer to the dopant and radiolysis products has been demonstrated. A nonlinear concentration behavior of the H atoms in doped Ar matrices has been established. Real-time correlated monitoring of optical emissions (H atom and CH3 radicals), particle ejection, and temperature revealed a nonmonotonic behavior of optical yields with a strong luminescence flash after almost an hour of exposure, which correlated with the explosive pulse of particle ejection and temperature. The connection of this phenomenon with the processes of energy transfer and recombination reactions has been established. It is shown that the delayed explosive ejection of particles is driven by both the recombination of H atoms and CH3 radicals. This occurs after their accumulation to a critical concentration in matrices at a CH4 content C ≥ 1%.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Matrix-Assisted Processes in CH4-Doped Ar Ices Irradiated with an Electron Beam

Bludov,

Khyzhniy,

Uyutnov

et al. 2023

Methane

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Radiation-induced phenomena in thermally treated Kr matrices

Savchenko

Khyzhniy

Uyutnov

et al. 2023

Low Temperature Physics

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The effect of thermal treatment on relaxation phenomena in Kr matrices irradiated with a low-energy electron beam has been studied. The experiments were carried out using measurements of the relaxation emissions of preirradiated Kr samples, which were unannealed and annealed before exposure to an electron beam. Three types of emissions were monitored in a correlated real-time manner: thermally stimulated luminescence, thermally stimulated exoelectron emission, and total yield of particles via pressure measurements. The energy levels of defects were estimated from the thermally stimulated luminescence data of the annealed sample. Two types of electron-hole traps created by electronic excitation were identified: close pairs and distant ones. Additional confirmation of the “excited state” mechanism of defect formation was obtained. Analysis of the correlation of yields and the effect of thermal treatment gave additional arguments in support of the crowdion model of anomalous low-temperature post-desorption from pre-irradiated Kr matrices.

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Matrix Assisted Processes in CH4-Doped Ar Ices Irradiated with an Electron Beam

Bludov¹,

Khyzhniy²,

Uyutnov³

et al. 2023

Preprint

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The relaxation processes induced by an exposure of the Ar matrices doped with CH4 (0.1 – 10%) to an electron beam were studied with a focus on the dynamics of radiolysis products – H atoms, H2 molecules, CH radicals, and energy transfer processes. Three channels of energy transfer to dopant and radiolysis products were discussed: by free charge carriers, free excitons and photons from the “intrinsic source” provided by emission of the self-trapped excitons. Radiolysis products along with the total yield of desorbing particles were monitored in a correlated manner. Analysis of methane transformation reactions induced by free excitons showed that the CH radical can be considered as a marker of the CH3 species. The competition between exciton self-trapping and energy transfer to the dopant and radiolysis products has been demonstrated. A nonlinear concentration behavior of the H atoms in doped Ar matrices has been established. Real-time correlated monitoring of optical emissions (H atom and CH3 radicals), particle ejection, and temperature revealed a nonmonotonic behavior of optical yields with a strong luminescence flash after almost an hour of exposure, which correlated with explosive pulse of particle ejection and temperature. The connection of this phenomenon with the processes of energy transfer and radical-radical recombination is discussed.

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Explosive desorption induced by radical–radical interaction in methane-doped Ar matrices

Cited by 3 publications

References 38 publications

Matrix-Assisted Processes in CH4-Doped Ar Ices Irradiated with an Electron Beam

Matrix-Assisted Processes in CH4-Doped Ar Ices Irradiated with an Electron Beam

Radiation-induced phenomena in thermally treated Kr matrices

Matrix Assisted Processes in CH4-Doped Ar Ices Irradiated with an Electron Beam

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