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Modern scanning electron imaging (SEM) has become an essential tool in various fields. In order to obtain high‐quality images with minimal vibration and drift, the multi‐frame stacking technique is commonly used. However, one aspect that has been overlooked in this process is the electron beam‐induced temperature effect. This study aims to explore the impact of the temperature effect on SEM contrast for a single spherical nanoparticle, specifically a gold nanosphere on a carbon substrate. Through Monte‐Carlo simulation, we investigated how the number of frames in multi‐frame stacking mode affects two types of electron signals: secondary electrons (SE) and backscattering electrons (BSE). Our findings revealed that the SEM contrast is indeed sensitive to the number of frames used in the stacking process. It is observed that the SE contrast decreases while the BSE contrast increases compared to cases without considering temperature effects. It is also found that when using the large primary electron beam energy, the impact of temperature effect was less significant. The electron‐solid interaction theory was utilized to systematically explain the underlying mechanism. This study not only sheds light on how temperature effects can influence SEM imaging but also provides valuable insights for optimizing image acquisition techniques. [ABSTRACT FROM AUTHOR]

Morphological evaluation of the small intestine mucosa and apoptosis activity (caspase-3) is necessary to assess the severity of damage to the small intestine. At the same time, proliferative index based on Ki-67 can be used to assess the regenerative potential of the small intestine. Fragments of small intestine of Wistar rats (n=60) of three groups: I) control (n=20); II) experimental group (n=20; local single electron irradiation at a dose of 2 Gy), III) experimental group (n=20; local single electron irradiation at a dose of 8 Gy) were studied by light microscopy using hematoxylin and eosin staining and immunohistochemical reactions with antibodies to Ki-67 and caspase-3. In all samples of the experimental groups, a decrease in all morphometric indices was observed on day 1 with a tendency to recover on day 3. Small intestinal electron irradiation led to disturbances in the histoarchitecture of varying severity, and an increase in cell apoptosis was observed (increased expression of caspase-3 and decrease in Ki-67). In addition, modulation of the PI3K/AKT and MAPK/ERK signaling pathways was detected. The most pronounced destructive changes were observed in the group of 8 Gy single electron irradiation. Local irradiation of the small intestine with electrons at a dose of 2 and 8 Gy results in a decrease in the number of enterocytes, mainly stem cells of the intestinal crypts. [ABSTRACT FROM AUTHOR]

The effect of irradiation with different doses of 4-MeV electrons on radiative recombination of nonequilibrium charge carriers in Cu(In,Ga)(S,Se)2 thin films of solar cells was studied. Near-edge photoluminescence (PL) in the energy range ~0.9–1.2 eV in nonirradiated and irradiated direct-gap Cu(In,Ga)(S,Se)2 solid solutions was caused by optical interband transitions and radiative recombination through energy levels of acceptor- and donor-type structure defects in the presence of strong potential fluctuations. PL spectra measured in the temperature range 5–300 K exhibited energy shifts of the near-edge PL band maxima and redistributions of their intensities in thin films after irradiation with different doses of electrons. The activation energies of nonradiative recombination were determined from the quenching of PL band intensities. The possible nature of structural defects in nonirradiated and electron-irradiated Cu(In,Ga)(S,Se)2 solid solutions was discussed. [ABSTRACT FROM AUTHOR]

4H-SiC metal-oxide-semiconductor (MOS)-based devices appear to worse electrical performance when exposed to electron irradiation, owing to the production of material defects. This study demonstrates an analysis of defect evolution of 4H-SiC MOS capacitors with the simplest structure, subjected to a series dose of electron irradiation with 10 MeV electron beam, including 30, 50, 100, 500, 1 000 kGy. Deep level transient spectroscopy (DLTS) test and capacitance-voltage (C-V) measurement were used to obtain defects information among MOS samples pre- and post-irradiation. DLTS results present that a low dose of irradiation causes no evident impact on defect evolution near and at the 4H-SiC/SiO2 interface, whereas a high dose of irradiation makes a defect configuration of carbon interstitial dimer defect evolve into another more stable one at a deeper energy level. C-V curves show that different irradiation doses lead to different negative shift degrees of flat-band voltage. This is considered to be resulted from multiple factors, including oxygen vacancies in the SiO2 layer and defects near and at the 4H-SiC/SiO2 interface. This work might be helpful for the development and optimization of 4H-SiC MOS fabrication with respect to anti-irradiation performance. [ABSTRACT FROM AUTHOR]

MgKPO4·6H2O (magnesium potassium phosphate-based cement; MKP) is an environment friendly alternative to Portland cement with potential applications in environmental remediation and radioactive nuclear waste management, particularly in the context of β-emitting Cs and Sr immobilizations. Thus, investigation of the radiation effects and temperature due to decay heat in such material is of prime importance. In this study, MgKPO4·6H2O powders were synthesized and subsequently annealed at 1273 K for 2 h under ambient atmosphere to form MgKPO4. The synthesized and annealed MKP specimens were irradiated under ambient conditions with 10-MeV electron beam up to imparted doses of 20 MGy. XRD results reveal the formation of amorphous fraction in irradiated MgKPO4·6H2O, while the annealed MKP specimens exhibit good radiation stability without amorphization. The annealed specimens also indicated good thermal stability when compared to as-prepared MgKPO4·6H2O specimen both in pristine and irradiated conditions. Vibrational spectroscopic results confirm that the radiation effect resulted in distortion/removal of structural water and formation of radiolysis products in MgKPO4·6H2O. [ABSTRACT FROM AUTHOR]

The rapid development of aerospace electronics towards lightweight and miniaturized designs has put forward higher requirements for the reliability of device interconnection. It is crucial to study the effects of space radiation and thermal cycle environments on the performance of micro-solder joints. This study uses experimental and simulation methods to study the comprehensive effects of electron irradiation and thermal cycling on the mechanical and electrical properties of Sn-3.0Ag-0.5Cu (SAC305) micro-solder joints. The results show that the combined effect of electron irradiation at a dose of 100 Mrad(Si) and 200 thermal cycles causes the operating temperature of the resistor in the sample to increase while severely reducing the shear strength of the solder joint. Two fracture modes, brittle and plastic, are observed in solder joints during the shearing process. As the number of thermal cycles increases, the proportion of plastic fracture increases. The combined effects of electron irradiation and thermal cycling exacerbate the deterioration of the shear strength of solder joints, with the shear strength of solder joints with brittle fractures decreasing by 28.00% and those with plastic fractures decreasing by 23.34%. [ABSTRACT FROM AUTHOR]

Abstract A method has been developed to increase computational efficiency in Monte Carlo simulations of electron transport and interactions in matter. The method serves as the computational engine for the open-source code AMCSET (Aggie Monte Carlo Simulations of Electron and Ion Transport). The key is to combine n consecutive neighboring free flying distances into groups. Within each group, both flying distance and Mott scattering angles are obtained using Monte Carlo sampling under an equal energy approximation. This reduces the number of integrations of the tabulated differential Mott scattering cross-section in scattering angle selection, i.e., from 1000 to 1 if n = 1000. The method increases efficiency by more than 100 times. At the same time, the calculation still guarantees accuracy in calculating electron trajectory, excitation/ionization energy deposition, elastic scattering energy deposition, and displacement creation. For demonstration, 10 MeV electron bombardments of pure Fe with n up to 1000 are used as examples. The method, due to the availability of tabulated scattering cross-sections, is applicable for targets of the entire elemental table up to Z = 118, and for electron energies up to 900 MeV.

The FTIR absorption bands of virgin and electron-irradiated CeO2 single crystals were measured from 20 K to 500 K between 4000 cm−1 and 12,000 cm−1 (~830 nm to 2500 nm). Three broad bands centered at about 6100 cm−1 (~0.75 eV), 7000 cm−1 (~0.87 eV), and 10,500 cm−1 (~1.3 eV) were recorded above 100 K for the 2.5 MeV electron energy. Two smaller bands at about 4300 cm−1 (~0.53 eV) and 5500 cm−1 (~0.68 eV) were also recorded below 100 K. Similar broad bands centered at about 4100 cm−1 (~0.52 eV), 6400 cm−1 (~0.79 eV), 7600 cm−1 (~0.94 eV), and 10,500 cm−1 (~1.3 eV) are also found for the 1.4 MeV electron energy above 300 K. The evolution of these absorption bands was followed as a function of temperature. The plots of band intensity ratios show a thermally activated process corresponding to the ionization of the deep electronic levels of point defects in the band gap of ceria of ~26,000 cm−1 (~3.2 eV). These five bands are assigned to the different charge states (0, −1, −2, −3, −4) of the Ce vacancies produced by elastic collisions above 1.0 MeV. [ABSTRACT FROM AUTHOR]

Medium-fluence fast electron irradiation (1019 e/cm2 to 1020 e/cm2) or the changes in the praseodymium concentration in the range of 0.0 ≤ z ≤ 0.5 on the excess conductivity of YBa2Cu3O7–δ single crystals ware investigated. These can lead to a wider range of the temperature interval of excess conductivity which narrows the interval of linearity in the ab plane. At fluences 0 ≤ Φ ≤ 6.5 × 1019 e/cm2, there was a threefold increase in the transverse coherence length ξc(0) with an increase in Φ of more than four times as the praseodymium concentration increased to z ≈ 0.42. The two-dimensional–three-dimensional (2D–3D) crossover point shifted upward in temperature. Conversely, to irradiation with low fluences (Φ ≤ 1019 e/cm2) or low praseodymium doping (z ≤ 0.39), irradiation with medium fluences or high praseodymium doping led to a non-monotonic dependence of ξc(0) on the irradiation fluence, with characteristic maxima at Φ~(7–8) × 1019 e/cm2 and z ≈ 0.42, likely due to the suppression of the superconducting characteristics. [ABSTRACT FROM AUTHOR]

A method has been developed to increase computational efficiency in Monte Carlo simulations of electron transport and interactions in matter. The method serves as the computational engine for the open-source code AMCSET (Aggie Monte Carlo Simulations of Electron and Ion Transport). The key is to combine n consecutive neighboring free flying distances into groups. Within each group, both flying distance and Mott scattering angles are obtained using Monte Carlo sampling under an equal energy approximation. This reduces the number of integrations of the tabulated differential Mott scattering cross-section in scattering angle selection, i.e., from 1000 to 1 if n = 1000. The method increases efficiency by more than 100 times. At the same time, the calculation still guarantees accuracy in calculating electron trajectory, excitation/ionization energy deposition, elastic scattering energy deposition, and displacement creation. For demonstration, 10 MeV electron bombardments of pure Fe with n up to 1000 are used as examples. The method, due to the availability of tabulated scattering cross-sections, is applicable for targets of the entire elemental table up to Z = 118, and for electron energies up to 900 MeV. [ABSTRACT FROM AUTHOR]

Gallium nitride (GaN), renowned for its inherent characteristics such as a high threshold potential and wide-band gap, stands as a promising candidate for the development of semiconductor devices intended for deployment in demanding radiation environments. This paper meticulously investigates the repercussions of electron irradiation on the intricate electrical properties of Ni/Pd/n-GaN Schottky barrier diodes (SBDs). The Ni/Pd/n-GaN SBDs underwent irradiation with 10 MeV electrons, encompassing varying doses ranging from 15 kGy to 149 kGy. A comprehensive analysis of alterations in diverse electrical properties of the SBDs was conducted, employing methodologies derived from Current-Voltage (I–V) characteristics. The electron-irradiated devices exhibited maximal deviation from their pristine state at a dose of 15 kGy, potentially attributable to annihilation or restructuring of traps within the semiconductor. Remarkably, deviations in ideality factor (n) and barrier height (ϕB) were inconsequential at doses of 75 and 149 kGy. Conversely, a notable escalation in series resistance was observed at 149 kGy, indicating a pronounced deterioration in the overall device properties. Additionally, an exploration of the charge transport mechanisms revealed a discernible influence of thermionic emission and various current transport mechanisms on the irradiated Ni/Pd/n-GaN SBDs. The outcomes of this investigation not only provide crucial insights into the nuanced changes induced by electron irradiation on the electrical characteristics of Ni/Pd/n-GaN Schottky diodes but also offer valuable information for the development of semiconductor devices resilient to the challenges posed by harsh radiation environments. This study contributes to the evolving understanding of GaN-based devices and their potential applications in radiation-rich scenarios. [ABSTRACT FROM AUTHOR]

As the feature size of integrated circuit decreases, the critical charge of single-event effect decreases as well, making nano-scale devices more susceptible to the high-energy charged particles during their application in space. Here, we study the electron-induced single-event effect in 28 nm static random-access memory (SRAM)-based field programmable gate array (FPGA) utilizing high-energy electrons with energy of 1 MeV~5 MeV. The experimental results demonstrate that the 3 MeV electrons can cause single-event functional interrupts (SEFIs) in FPGA, while the electrons with other energies cannot. To further explore the mechanism of electron-induced SEFIs in this nanoscale FPGA, we combined Monte Carlo, Technology Computer-Aided Design (TCAD), and Simulation Program with Integrated Circuit Emphasis (SPICE) simulations. It is revealed that the SEFI was mainly caused by the direct ionization effect of high-energy electrons, and the SEFI was related to the interactions between multiple sensitive nodes. [ABSTRACT FROM AUTHOR]

Power electronic devices face harsh radiation environments in deep space exploration. It is significant to study the reliability of solder joints of electronic devices in radiation environments. The effect of electron irradiation on the microstructure and mechanical properties of Sn3Ag0.5Cu (SAC305) Ball Grid Array (BGA) solder joints was investigated in this work. The results show that the central position of the SAC305 solder joint surface was damaged after electron irradiation. Then the surface of the solder joints was remelted. The shear strength of solder joints increases as the electron irradiation dose rises. When the electron irradiation dose reaches 80 Mrad, the shear strength of the solder joint is enhanced by 8.62% compared with that of the unirradiated sample. After irradiation, the number of dimples on the fracture surface of solder joints increases and the depth of dimples decreases. Geant4 simulation results show that the surface of solder joint is subject to more severe electron impact than the inside of solder joint is. The interaction between electrons and solder joints is the primary reason for the surface remelting of solder joints.

In this work, the phase transition process of β-Ga2O3 thin films under heating and (or) electron irradiation condition was investigated by in-situ transmission electron microscopy. It is found that only under the high temperature, β-Ga2O3 did not undergo phase transition even when the temperature was up to 1000 °C. When under electron irradiation condition, the unconventional phase transition from β-Ga2O3 to δ-Ga2O3 occurred with a slow rate. When electron irradiation was coupled with a thermal field, the initial temperature of phase transition decreased, and the speed of phase transition also greatly accelerated. The new phase maintains crystallography relationship with the β-Ga2O3 parent phase as following: [010]β//[011‾]δ, (200)β//(2‾11)δ, and (402‾)β//(411)δ. The results reveal that electron irradiation can trigger the phase transition process from β-Ga2O3 to δ-Ga2O3, and the high temperature obviously accelerates the rate of phase transition process.

Latvian Darkhead (LD) is a local sheep breed and a genetic resource in Latvia. Preservation and development of the sheep population in the local region is important for the recultivation of fields, it serves as a source for export and local use, as well as waste wool can be applied for developing new products, for example, sorbents for volatile organic pollutants. Therefore, investigation of the sorption properties of the LD sheep wool fibers is under interest. In addition, modification options of the wool for improvement of properties are viewed. Therefore, in the present work, sheep wool fibers as well as accelerated electron-irradiated fibers are analyzed and compared. Fourier transform infrared (FTIR) spectrometry is applied to develop the sorption testing system of volatile organic compounds. An analytical system consisting of a volatile organic compound source, sheep wool filter, and FTIR spectrometry cell is tested and applied for analysis of wool sorption properties for acetone molecules. Registration of the FTIR spectra was performed within the range of 600-4000 cm-1, in the nitrogen flow of about 150mL/min. FTIR analysis shows, that the accelerated electron irradiated sheep wool fibers absorb acetone of about 33% more than non-irradiated fibers. The obtained results will be used for developing recommendations for filter producers to fabricate filter components containing LD sheep wool fibers.

Attenuated total internal reflection (ATR) spectra of polyimide PI-2610 films deposited on single-crystal silicon wafers by centrifugation were studied after irradiation with 5-MeV electrons in a linear accelerator at doses of 1∙1014–2∙1015 cm–2. The strongest bands in the spectrum of the PI-2610 polyimide films were attributed to vibrations of the imide ring C–N–Cst (1349 cm–1) and aromatic ring (1517 cm–1), stretching vibrations of the imide ring C=Ostr (1700 cm–1) and CO–Cst-group C–C bonds (1074 cm-1), and bending vibrations of C–H bonds with maxima at 734 and 828 cm–1. The spectral shape and intensities of bands with maxima at 1700 and 1349 cm–1 due to C=O and C=N–Cstr vibrations were observed to change at an initial dose of 1∙1014 cm–2. It was assumed that this was due to relaxation of metastable states of these groups. The intensities of bands corresponding to asymmetric and symmetric stretching vibrations of C–H2 bonds decreased at a dose of 2∙1015 cm–2. The intensities of ATR bands due to vibrations of C=O and C–N bonds and aromatic and imide rings practically did not change. [ABSTRACT FROM AUTHOR]

Surrogate tristructural isotropic (TRISO) particles, including ZrC and SiC layers, were manufactured through fluidized-bed chemical vapor deposition and irradiated. ZrC layers exhibited C/Zr atomic ratio of 0.95 without distinct crevices at interfaces in microscopy, but underwent significant microstructural changes post-irradiation. Defects included black dots and Frank loops, with increasing irradiation doses augmenting their area fractions. Frank loop density reduced at 9.4 dpa due to the formation of fewer, fully circular loops. The ZrC hardness and modulus rose by 25% and 26% following Ar-ion irradiation at 9.4 dpa, linked to the formed defects and implanted Ar ions. Electron irradiation expanded the defect-prone zone up to 100 nm from the ZrC grain boundary and led to ZrO 2 formation. ZrC grains recrystallized post electron irradiation at 700 °C, causing initial grain decomposition, amorphization, and nanocrystal formation. These nanocrystals, formed at 3.3 dpa, closely aligned with ZrC diffraction patterns with no preferred orientations. [ABSTRACT FROM AUTHOR]

Silicon carbide (SiC) with the advantages of high thermal conductivity and high breakdown field strength can meet the new requirements of modern electronic technology for harsh conditions. Focusing on the application of deep space exploration, the present work has explored the effects of 2-MeV electron irradiation on 4H-SiC with a fluence of 7 × 1012 cm–2 and 1 × 1013 cm–2. The samples irradiated with 2-MeV electrons and 1 × 1013 cm−2 fluence have a smaller full width at half-maximum (FWHM) in both x-ray diffraction (XRD) and Raman spectra, weaker defect luminescence intensity in photoluminescence (PL) spectra, and increased Si-C bond ratio in x-ray photoelectron spectroscopy (XPS). These demonstrated that the electron irradiation at 2 MeV with the fluence of 1 × 1013 cm–2 has caused the crystallization performance to recover in comparison with the original sample. The improved crystal quality can be ascribed to the thermal effects produced during the electron irradiation. [ABSTRACT FROM AUTHOR]

Latvian Darkhead (LD) is a local sheep breed and a genetic resource in Latvia. Preservation and development of the sheep population in the local region is important for the recultivation of fields, it serves as a source for export and local use, as well as waste wool can be applied for developing new products, for example, sorbents for volatile organic pollutants. Therefore, investigation of the sorption properties of the LD sheep wool fibers is under interest. In addition, modification options of the wool for improvement of properties are viewed. Therefore, in the present work, sheep wool fibers as well as accelerated electron-irradiated fibers are analyzed and compared. Fourier transform infrared (FTIR) spectrometry is applied to develop the sorption testing system of volatile organic compounds. An analytical system consisting of a volatile organic compound source, sheep wool filter, and FTIR spectrometry cell is tested and applied for analysis of wool sorption properties for acetone molecules. Registration of the FTIR spectra was performed within the range of 600-4000 cm-1, in the nitrogen flow of about 150mL/min. FTIR analysis shows, that the accelerated electron irradiated sheep wool fibers absorb acetone of about 33% more than non-irradiated fibers. The obtained results will be used for developing recommendations for filter producers to fabricate filter components containing LD sheep wool fibers. [ABSTRACT FROM AUTHOR]

In this work, we study the effect of 6 MeV electron beam irradiation on the physicochemical properties of lyophilized Human Haemoglobin A (HbA). Electron beams generated from Race Track Microtron accelerator with energy 6 MeV were used to irradiate HbA at fluences of 5 × 1014 e−/cm2 and 10 × 1014 e−/cm2. Pristine and electron beam irradiated HbA were characterized using UV-visible and Fourier transform infrared spectroscopy (FTIR) spectroscopy. The interfacial tension of the aqueous solutions of HbA are also analysed by pendant drop method. Absorbance intensity, % transmittance and interfacial tension decrease with fluence. The peak position of the Soret band (λsoret = 404 nm) remains unaffected by the fluences. FTIR spectroscopy confirms the changes in the secondary structure of the haemoglobin. In the amide band I, the percentage of α-helix reduced from 8% to 1%, and an increase in β-sheet (19% to 29%) and β helix (6.3% to 15%) is observed. Interfacial tension decreases from 46.0 mN/m and 44.0 mN/m with increase in irradiation dose. These finding provides realistic guideline for biological cells exposure to electron beam radiation doses. [ABSTRACT FROM AUTHOR]

Due to good thermal conductivity and thermal shock resistance, ultra-high temperature ceramics such as zirconium diboride (ZrB2) have been investigated as promising materials to be used in reusable thermal protection systems TPSs are vital to the heat balance of a spacecraft during atmospheric reentry and subsequent operation in space. Hence, the thermal and optical properties are especially critical for such applications. Meanwhile, radiation exposure in space can pose risks of degrading such material properties, especially over a prolonged mission duration. The interaction of electron radiation-which can be found in the outer Van Allen belt, with ZrB2 has not been studied previously and was chosen as the main scope of this study. An electron source of 3 MeV with different radiation exposure time was used. The response of thermo-optical properties of ZrB2 to increasing electron radiation fluences was investigated. ZrB2 samples were made through spark plasma sintering into sintered pellets and then exposed to 3 MeV electron irradiation. These ZrB2 samples were characterized by their microstructure, thermal conductivity, coefficient of thermal expansion (CTE), emittance, absorptivity, and surface roughness before and after irradiation. It was found that ZrB2's thermo-optical properties showed high radiation resistance at these fluences, and no apparent microstructural change was observed after irradiation. However, the irradiated samples had, on average, a 29% lower surface roughness than the unirradiated samples, possibly originating from electron sputtering. [ABSTRACT FROM AUTHOR]

The protection of satellites from the harsh space environment is heavily reliant on external spacecraft materials. These materials undergo continuous changes in their physical, chemical, and optical properties due to exposure to solar radiation and aggressive chemical species present in Earth's upper atmosphere. By gaining a thorough understanding of how these material properties evolve over the planned lifetime of a mission, the reliability of spacecraft can be enhanced. Additionally, the establishment of correlation factors between actual space exposure and accelerated space weather experiments performed in ground facilities allows for the precise prediction of on-orbit material performance based on laboratory-based testing. This paper presents an assessment of the radiation effects of the low Earth orbit environment, including exposure to high-energy electrons, atomic oxygen, and vacuum ultraviolet, on the material properties of a prospective spacecraft polymer, Mylar® M021. The study is part of the 16th Materials International Space Station Experiment (MISSE), which our team conducted from 08/31/22 to 02/23/23. An overview of the MISSE project is provided, including details on the materials used, results of ground experiments, and preliminary findings from the orbital phase of the study. [ABSTRACT FROM AUTHOR]

The work investigates the processes determining the characteristics of the method of increasing the effectiveness of the antitumor effect of doxorubicin without the use of extraneous nanoimpurities. The method is based on the use of high-energy electron irradiation of physiological saline (PS) before dissolving doxorubicin in it. The energy of the irradiation electrons is equal to 1 MeV, and the absorbed dose (gray) is in the range of 4–80 kGy. Doxorubicin (Sigma, USA) is used in the study, and the Lewis lung carcinoma cell line (LLC) given by the R. E. Kavetsky Institute of Experimental Pathology, Oncology and Radiobiology (IEPOR), National Academy of Sciences of Ukraine is used to determine the pharmacological characteristics of doxorubicin. It is proven that the amount of the absorbed dose affects the optical absorption and fluorescence spectra of the samples and leads to an increase in the cytotoxic/cytostatic effect of the drug, which is most pronounced at relatively low concentrations. The number of live LLC cells under the influence of doxorubicin in the irradiated solvent at concentrations less than 3 μM is decreased to 15% compared to the corresponding indicator under the action of doxorubicin without irradiation of the solvent. A comparative study of the acute toxicity of irradiated PS is carried out. The results of the study do not provide convincing data that would indicate differences in the toxicity profiles of irradiated and non-irradiated PSs. [ABSTRACT FROM AUTHOR]

The response and mechanism of polyimide aerogel under electron irradiations were investigated. The experimental results indicated that electron irradiation could not damage the skeleton polyimide in the aerogel due to its high stability, but could result in a discharge within. The morphology of the discharge shows some dendritic discharge patterns, and the material surrounding the discharge channels was carbonized. The numerical simulation results indicated that the incident electrons, and also large amount induced secondary electrons, would be deposited inhomogeneously within the nano-porous polyimide aerogel. This would result in forming an ultra-high electrical potential of up to about 8.5 × 1010 V/m (which is far higher than the breakdown strength (2 × 108 V/m) of bulk polyimide materials) in a local region. This may be the leading cause of the obvious discharge in the materials. Furthermore, it was found that the actual reason for the discharge is related to the residual gas within the nano-porous structure; namely, the more internal residual gas (as a shorter-time vacuum pumping in the irradiated chamber), the more serious the discharge phenomenon. Correspondingly, the phenomenon may largely consist of both residual-gas discharge and surface flashover due to ultra-high local potentials induced by unevenly deposited charges in the porous aerogel. [ABSTRACT FROM AUTHOR]

We performed 1.5MeV electron-irradiation at 333K and 533K for Cu-4.2 at％ Ti alloy with a single phase of super-saturated solid solution, and investigated the irradiation-induced changes in Vickers hardness and electrical conductivity. With increasing the electron fluence, both of the hardness and the electrical conductivity increase. Such phenomena can be ascribed to the formation of Ti-rich precipitates that are caused by irradiation-enhanced diffusion of Ti atoms. The increase in electrical conductivity is caused by the reduction of Ti content in Cu matrix because of the formation of Ti-rich precipitates. The increase in hardness is also caused by Ti-rich precipitates that are effective obstacles against the motions of dislocations. We found a clear correlation between the irradiation-induced change in the hardness, ΔHv and change in electrical resistivity, Δρ, or that in electrical conductivity, Δσ, as.... This correlation suggests that the precipitate-cutting mechanism governs the irradiation-induced increase in hardness; that is, 1.5MeV electron-irradiation at relatively low temperatures of 333K to 533K should promote the nucleation of fine Ti-rich precipitates preferentially rather than the growth of them. The present result shows that energetic electron irradiation is a good tool to improve the mechanical and electrical properties of Cu-Ti alloys. [ABSTRACT FROM AUTHOR]

The introduction of strain InxGa1-xAs channel with high In content increases the confinement of the two-dimensional electron gas (2DEG) and further improves the high-frequency performance of InGaAs/InAlAs/InP HEMTs. The effect of InxGa1-xAs channel with different In contents on electron irradiation tolerance of InP-based HEMT structures in terms of 2DEG mobility and density has been investigated. The experiment results show that, after the same high electron irradiation dose, the 2DEG mobility and density in InP-based HEMT structures with strain InxGa1-xAs (x＞0.53) channel decrease more dramatically than that without strain In0.53Ga0.47As channel. Moreover, the degradation of 2DEG mobility and density becomes more severe as the increase of In content and strain in the InxGa1-xAs channel. The research results can provide some suggestions for the design of radiation-resistant InP-based HEMTs.

Background: Skin cancer is the most frequently diagnosed type of cancer among all malignant neoplasms. The decrease in mitotic activity and the death of intact keratinocytes arise due to the constantly renewing epithelium is highly sensitive to ionising radiation. Aim: The aim of the study is immunohistochemical evaluation of the proliferative-apoptotic balance of keratinocytes, the fibrous component of the skin and the expression of pro-inflammatory and anti-inflammatory cytokines after single or fractional local electron irradiation. Methods: Wistar rats (n=80) were taken from the ITM&B Vivarium (Sechenov University) and divided into groups: I – control, which were injected with saline; and experimental groups, local electron irradiation at doses: II – 8 Gy (single), III – 40 Gy (single), IV – summary dose 78 Gy (fractional; 13 Gy per day for 6 days). We performed histological analysis, histochemical analysis using Masson, safranine and picrosirius red staining, immunohistochemical (Ki-67, caspase-3, p53, types I and III collagens, IL-1, IL-6, IL-4 and IL-10) and morphometric analysis of skin fragments of the outer surface of the thigh, irradiated in accordance with the design of the experiment. The early and delayed effects of local electron irradiation at different doses were studied. Results: After local electron irradiation, dose-dependent morphological changes in the skin of the experimental groups were observed: violation of the histoarchitectonics of the skin confirmed by morphological and morphometric analysis, proliferation of connective tissue according to the results of histochemical and immunohistochemical studies with signs of the radiation-induced skin fibrosis development, an increase in the levels of pro- and anti-inflammatory cytokines. We observed the most pronounced signs of the radiation-induced skin damage in the group of fractional irradiation after three months. Conclusion: 8 Gy and 40 Gy single local electron irradiation leads to a shift in the proliferative-apoptotic balance of keratinocytes towards their apoptosis, which activity is directly correlate with the dose of ionizing radiation, and 78 Gy in fractions leads to partial desquamation of the epithelium and inflammatory infiltration. In addition, after three months a significant increase in the expression of type I and type III collagen fibers and the development of radiation-induced skin fibrosis takes place against the background of 78 Gy fractional local electron irradiation. [Open Vet J 2023; 13(12.000): 1570-1582]

In this work, the effect of irradiation with 5-MeV electrons on the adhesive and strength properties of the films of diazoquinone–novolac photoresists FP9120, SPR-700, and S1813 G2 SP15 deposited on single-crystalline silicon wafers by spin-coating has been studied using the indentation method. It has been established that irradiation leads to an increase in the true microhardness of the photoresist films, most pronounced in SPR-700 films, caused by the crosslinking of phenol–formaldehyde resin molecules. It has been shown that the values of the specific peeling energy G of photoresist films on silicon increase upon irradiation as a result of the recombination of radicals at the photoresist/silicon interface with the formation of new covalent bonds Si–C and Si–O–C. The observed experimental results are explained taking into account the radiation-chemical and relaxation processes occurring in the bulk of the polymer film and at the interface. [ABSTRACT FROM AUTHOR]

Scanning electron microscope (SEM) is widely used in imaging rather than for thermometry. In this work, the temperature-dependent line-scan profile for a silicon (Si) pitch structure was investigated by a simulation approach. Various electron signals (secondary electron (SE) and backscattering electron (BSE)) were recorded with different values of temperature at various primary electron (PE) energies. It is found that both the SE and BSE line-scan profiles vary with the temperature. However, the BSE line-scan profile presents a lower contrast than that of the SE profile. The deposited energies contributed by full electrons, Pes, and cascaded electrons as functions of depth and radial direction at different temperatures for this pitch structure were also investigated. It was concluded that the influences of the temperature of a solid on the scattering processes of PEs and cascaded electrons are different. Possible mechanisms were systematically analyzed based on the theory of electron–solid interaction. Finally, the temperature effect on the pitch measurement based on a line-scan profile was also investigated through the maximum derivative method. It was found that the bias value slightly increases with temperature. This work poses a potential possibility of measuring the temperature of nanostructures by acquiring the temperature-dependent line-scan profile by a standard SEM. [ABSTRACT FROM AUTHOR]

Spacecraft materials play a crucial role in safeguarding satellites from space’s harsh conditions. However, exposure to solar radiation and aggressive chemical species in the upper atmosphere alters these materials’ physical, chemical, and optical properties over time. Understanding material evolution during a mission enhances spacecraft reliability. By establishing correlations between on-orbit material performance and laboratory-based tests, accurate predictions can be made through accelerated space weather experiments. This study evaluates the effects of radiation on various modern spacecraft materials, specifically high-energy electrons, atomic oxygen, and vacuum ultraviolet radiation, in a ground-based simulated LEO environment. The focus is on assessing the impact on the Bidirectional Reflectance Distribution Function properties. [ABSTRACT FROM AUTHOR]

Photoresist (PR) NFR 016D4 films deposited on the surface of silicon (Si) wafers by centrifugation were studied by attenuated total internal reflection Fourier-IR spectroscopy. Background absorption of the PR/Si structures was observed to increase at wave numbers <1600 cm−1 because of the effect of electromagnetic radiation on the Si substrate and scattering/reflection at the PR/Si interface. Asymmetry in the force field of the aromatic ring in the NFR 016D4 film was detected. Spectral features of thick PR NFR 016D4 films were due to the presence of residual solvent. Formaldehyde formed by fragmentation of hydroxymethyl residues in the phenol-formaldehyde resin was detected in irradiated films. Radiation-induced processes in PR NFR 016D4 films at doses up to 2∙1015 cm−2 involved mainly residual solvent molecules or by-products of PR film synthesis. [ABSTRACT FROM AUTHOR]

The scanning electron microscope (SEM) is primarily used for imaging observation rather than as a tool for thermometry. This study explores the temperature‐dependent electron emission with a main focus on the line‐scan profile of two systems: one consisting of beryllium (Be) nanospheres (Be‐NS) and another consisting of gold (Au) NS (Au‐NS) on a Be substrate using Monte Carlo simulation. The relations between two types of electron signals with the temperature and the sample size at different primary electron (PE) energies are first recorded. This study concludes that the shape of the secondary‐electron line‐scan profile changes with the temperature for various sizes of a NS both in Au/Be and in Be/Be systems. However, the shape of the backscattering electron line‐scan profile remains almost unchanged with the temperature in the Au/Be system, but exhibits obvious changes in the Be/Be system. This work next investigates the spatial distributions of the deposited electron energy resulting from full electrons, the PEs, and the cascaded electrons at different temperatures. It indicates that the inherent temperature exerts different influences on scatterings of PEs and the cascaded electrons. Utilizing the electron–solid interaction theory, a systematic explanation is provided for these findings. This study potentially offers a possibility for thermometry in nanostructures using SEMs. [ABSTRACT FROM AUTHOR]

Modern scanning electron imaging (SEM) frequently adopts the multi-frame stacking technique to minimize the vibration and drift but ignores the electron beam-induced thermal effect (called thermal effect hereafter for short) during the stacking. This study investigates the thermal effect on SEM contrast in multi-frame stacking mode for two systems, namely one gold nanorod (Au-NR) and one silicon nanorod (Si-NR) on a Si substrate through a Monte-Carlo approach (In short, Au/Si and Si/Si systems). The primary focus of this investigation was to explore the correlation between two distinct types of signals, namely secondary electrons (SE) and backscattering electrons (BSE), in relation to the number of frames. It was observed that the SEM contrast exhibited sensitivity to the frame. The stacking process generally led to a reduction in SE contrast and an increase in BSE contrast compared to the scenario without thermal effects. This is attributed to higher heat accumulation within the solid as more frames are stacked, resulting in electrons from NRs acquiring extra energy and consequently causing a deep penetration depth that inhibits most SEs from being emitted. However, it helps BSEs to emit because there is more conversion of low-energy Ses into BSE signals with assistance from the extra energy. Furthermore, it was found that the thermal effect had less impact on cases involving a large primary electron (PE) beam energy. This is mainly because the larger initial energy causes the smaller relative variation in electron energy. Details of the explanation of the mechanism behind these results were given systematically by the electron-solid interaction theory. This study advances our comprehension and clarification of the physical mechanism underlying electron-beam-induced deposition, thereby enhancing process control, performance, and reliability. [ABSTRACT FROM AUTHOR]

Effect of electron irradiation on electronic structure of Ni41Co6Mn43Sn10 alloys were investigated by X-ray absorption fine structure, X-ray magnetic circular dichroism spectrometry and Mössbauer spectrometry. The local coordination environment of magnetic element significant changes after electron irradiation, the change in the peak intensity of the Co L3 edge is opposite to the Ni/Mn element, indicating that there is an electronic exchange between them. The crystal field symmetry is broken, the hyperfine field Hin of the Ni41Co6Mn43Sn10 alloy increases from 8.80 to 9.06 T. Meanwhile, the spin magnetic moment of the Mn atom is significantly increased after electron irradiation. [ABSTRACT FROM AUTHOR]

Background: Skin cancer is the most frequently diagnosed type of cancer among all malignant neoplasms. The decrease in mitotic activity and the death of intact keratinocytes arise due to the constantly renewing epithelium being highly sensitive to ionizing radiation. Aim: The aim of the study is immunohistochemical evaluation of the proliferative-apoptotic balance of keratinocytes, the fibrous component of the skin, and the expression of pro-inflammatory and anti-inflammatory cytokines after single or fractional local electron irradiation. Methods: Wistar rats (n = 80) were taken from the ITM&B Vivarium (Sechenov University) and divided into groups: I--control, which were injected with saline; and experimental groups, local electron irradiation at doses: II--8 Gy (single), III--40 Gy (single), IV--summary dose 78 Gy (fractional; 13 Gy per day for 6 days). We performed histological analysis, histochemical analysis using Masson, safranine, and picrosirius red staining, immunohistochemical (Ki-67, caspase-3, p53, types I and III collagens, IL-1, IL-6, IL-4, and IL-10) and morphometric analysis of skin fragments of the outer surface of the thigh, irradiated in accordance with the design of the experiment. The early and delayed effects of local electron irradiation at different doses were studied. Results: After local electron irradiation, dose-dependent morphological changes in the skin of the experimental groups were observed: violation of the histoarchitectonics of the skin confirmed by morphological and morphometric analysis, the proliferation of connective tissue according to the results of histochemical and immunohistochemical studies with signs of the radiation-induced skin fibrosis development, an increase in the levels of pro- and anti-inflammatory cytokines. We observed the most pronounced signs of radiation-induced skin damage in the group of fractional irradiation after 3 months. Conclusion: 8 Gy and 40 Gy single local electron irradiation leads to a shift in the proliferative-apoptotic balance of keratinocytes toward their apoptosis, which activity is directly correlated with the dose of ionizing radiation, and 78 Gy in fractions leads to partial desquamation of the epithelium and inflammatory infiltration. In addition, after 3 months a significant increase in the expression of type I and III collagen fibers and the development of radiation-induced skin fibrosis takes place against the background of 78 Gy fractional local electron irradiation. [ABSTRACT FROM AUTHOR]

The features of hydrogen trapping under the irradiation of zirconium alloys E110 and E635 with an electron beam (400 eV, 0.8 mA/cm2) in various gaseous ambient containing oxygen and hydrogen (Ar + O2 + H2; Ar + H2O) are studied. The effect of surface temperature on the hydrogenation of zirconium alloys under electron irradiation is studied. It is shown that neither exposure nor electron irradiation in a gaseous ambient containing a mixture of H2 and O2 at 700 K for 20 h leads to a change in the hydrogen level in the E110 alloy, while hydrogen partially escapes from the E635 alloy during the experiment. The amount of hydrogen in zirconium alloys after exposure in a gaseous ambient containing H2O in a similar temperature–time regime also changes insignificantly; however, if the alloys are irradiated with electrons under these conditions, then they contain 1.5–2 times more hydrogen. When temperature of the samples is raised to 900 K, electron irradiation in the presence of water vapor, on the contrary, reduces the trapping of hydrogen in the E110 and E635 alloys, compared with exposure in the same gaseous ambient without irradiation. It is concluded that electron irradiation affects the balance of surface reactions of formation of hydroxyl groups from adsorbed water molecules and reverse reactions of formation of water molecules from surface hydroxyls. The direction of shifting the balance of these reactions depends on the surface temperature. [ABSTRACT FROM AUTHOR]

Rutile TiO 2 exhibits RTFM when it contains intrinsic defects or when external elements are doped into the material, which makes it an crucial substrate material for advancement of spintronics. By utilizing electron irradiation, intrinsic defects can be generated in rutile TiO 2 , and the type and concentration of defects can be controlled by adjusting the energy and fluence of the electron beam. In this study, rutile TiO 2 samples were subjected to electron irradiation at different fluences, and the resulting microstructure, magnetism, and optical properties were characterized. The findings reveal that all the samples exhibit RTFM, and the changes of M S and N S are similar with the variations of the concentration of V O. This serves as direct evidence that the intrinsic defects in rutile TiO 2 can induce RTFM and confirms that electron irradiation can regulate the RTFM of rutile TiO 2. [Display omitted] • The change of M S and N S are similar with the variations of the electron fluence. • The intrinsic defect V O present in rutile TiO 2 can induce RTFM. • 0.5 MeV electron irradiation can regulate the RTFM of rutile TiO 2. [ABSTRACT FROM AUTHOR]

Boron vacancies (VB–) in hexagonal boron -nitride (hBN) have sparked great interest in recent years due to their optical and spin properties. Since hBN can be readily integrated into devices where it interfaces a huge variety of other 2D materials, boron vacancies may serve as a precise sensor which can be deployed at very close proximity to many important materials systems. Boron vacancy defects may be produced by a number of existing methods, the use of which may depend on the final application. Any method should reproducibly generate defects with controlled density and desired pattern. To date, however, detailed studies of such methods are missing. In this paper, we study various techniques for the preparation of hBN flakes from bulk crystals and relevant postprocessing treatments, namely, focused ion beam (FIB) implantation, for creation of VB–s as a function of flake thickness and defect concentrations. We find that flake thickness plays an important role when optimizing implantation parameters, while careful sample cleaning proved important to achieve consistent results. [ABSTRACT FROM AUTHOR]

The introduction rates of electrically active radiation defects Δ N def / Δ Φ were studied as a function of 15.5 MeV energy proton radiation fluence Φ in n-type and p-type Si semiconductor crystals. The concentration of electrically active radiation defects N def was determined as the difference between the charge carrier concentration before n 0 and after n Φ irradiation, at room temperature. It was demonstrated that the concentration of electrically active radiation defects in silicon crystals produced by proton irradiation can be described by an empirical exponential function. The experimental results show that the introduction rate of electrically active radiation defects depends on the initial sample parameters, and during the initial phase of irradiation by protons it is significantly higher than that for 3.5 MeV energy electron irradiation. It was shown that samples with a low introduction rate of radiation defects are more resistant to the effects of particle irradiation. The charge carrier mobility in both n-type and p-type silicon crystals changes slightly as a result of proton irradiation, in contrast to the significant decreases observed under conditions of electron irradiation. In the case of proton irradiation, the resistivity of n-type and p-type silicon crystals increases exponentially with the level of radiation fluence. [ABSTRACT FROM AUTHOR]

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%. [ABSTRACT FROM AUTHOR]

The results of experimental studies of processes occurring on the surface of protective glasses of solar batteries and elements of reflective coatings of high-orbit artificial Earth satellites (AESs) when exposed to electrons with an energy of 30 keV are presented. The samples studied have been made on the basis of K‑208 glass, while the samples of reflective coatings differ in the presence of silver and stainless steel layers on the reverse surface of the glass plates, deposited sequentially by magnetron sputtering. The electron irradiation of the samples was carried out in a vacuum of 10–4 Pa at a particle flux density (φ) from 1 × 109 to 8 × 1012 cm–2 s–1. The surfaces of the samples before and after irradiation have been examined by atomic force microscopy (AFM). On the irradiated surface of glass samples, electrostatic discharges (ESDs) arise, the parameters of which are characterized by oscillograms of generated electromagnetic pulses. In addition, leakage currents to the metal substrate have been measured for elements of reflective coatings. It has been found that changes in the structure of the irradiated surface of the samples are attributed to the appearance of ESD traces and the formation of gas-filled bubbles. Moreover, changes in the back surface of glass plates have been presumably caused by shock waves formed when ESD occurs on the irradiated surface. The ESD frequency and leakage currents increase with increasing electron flux density in the specified range, but these dependences showed significant differences. Measurements at a constant value of φ = 2.0 × 1010 cm–2 s–1 have revealed that an increase in the electron fluence from 1014 to 5 × 1016 cm–2 led to a higher ESD frequency, while the amplitude of electromagnetic pulses decreases. [ABSTRACT FROM AUTHOR]

In this work, the electron irradiation effects and post-irradiation annealing (PIA) response on SiC MOSFETs were investigated and analyzed in terms of the evolution of oxide- and interface-trap charges after irradiation and PIA. It is found that the electron irradiation leads to the significant decrease of Ron, degraded blocking characteristics, and negative shift of capacitance characteristics, which can be ascribed to the promoted generation of positively charged oxide and interface traps by irradiation. Interestingly, these degraded electrical properties can be partly or completely recovered by room-temperature (RT) anneal, which is associated with the difference in the sensitivity to the oxide/interface charge variations in the channel, JFET, and termination region. Surprisingly, the positive charge in the oxide presents an incomplete recovery, which is suggested to result from the tunneling electrons from SiC and thus the subsequent electron capture by positively charged oxygen vacancy in the oxide. Whereas, the irradiation-induced interface-trap charges are fully eliminated even after RT anneal for 15 days. Deep-Level Transient Spectroscopy (DLTS) characterizations shows that the interface defects with the energy band from EC − 0.14 eV to EC − 0.7 eV are enhanced by irradiation and exhibits similar dependence on the filling pulse as the near-interface traps. However, the irradiation-induced interface state density (Dit) distributions show a recovery behavior after RT storage, which is suggested to be resulted from the change in the charge states of interface defects from the electron trapping.

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%.

The carrier removal rates during proton and electron irradiations of n-type GaN grown by metal-organic vapor phase epitaxy were determined. Irradiation was carried out with protons with energy of 15 MeV in the fluence range 0 ≤ Фр ≤ 5 × 1014 cm–2; the range of fluences when irradiated with electrons with energy of 0.9 MeV was 0 ≤ Фn ≤ 5 × 1016 cm–2. The value of the removal rate during proton irradiation, ηp ≈ 140 cm–1, is close to the lower limit of currently known values of ηp and indicates a sufficiently high level of radiation resistance of the studied material with respect to proton irradiation. The rate of carrier removal under the influence of electron irradiation, ηe is ≈0.47 cm–1 and corresponds to the typical values of ηe for type gallium nitride obtained by various methods. [ABSTRACT FROM AUTHOR]

The FTIR absorption bands of virgin and electron-irradiated CeO2 single crystals were measured from 20 K to 500 K between 4000 cm−1 and 12,000 cm−1 (~830 nm to 2500 nm). Three broad bands centered at about 6100 cm−1 (~0.75 eV), 7000 cm−1 (~0.87 eV), and 10,500 cm−1 (~1.3 eV) were recorded above 100 K for the 2.5 MeV electron energy. Two smaller bands at about 4300 cm−1 (~0.53 eV) and 5500 cm−1 (~0.68 eV) were also recorded below 100 K. Similar broad bands centered at about 4100 cm−1 (~0.52 eV), 6400 cm−1 (~0.79 eV), 7600 cm−1 (~0.94 eV), and 10,500 cm−1 (~1.3 eV) are also found for the 1.4 MeV electron energy above 300 K. The evolution of these absorption bands was followed as a function of temperature. The plots of band intensity ratios show a thermally activated process corresponding to the ionization of the deep electronic levels of point defects in the band gap of ceria of ~26,000 cm−1 (~3.2 eV). These five bands are assigned to the different charge states (0, −1, −2, −3, −4) of the Ce vacancies produced by elastic collisions above 1.0 MeV.

Medium-fluence fast electron irradiation (1019 e/cm2 to 1020 e/cm2) or the changes in the praseodymium concentration in the range of 0.0 ≤ z ≤ 0.5 on the excess conductivity of YBa2Cu3O7–δ single crystals ware investigated. These can lead to a wider range of the temperature interval of excess conductivity which narrows the interval of linearity in the ab plane. At fluences 0 ≤ Φ ≤ 6.5 × 1019 e/cm2, there was a threefold increase in the transverse coherence length ξc(0) with an increase in Φ of more than four times as the praseodymium concentration increased to z ≈ 0.42. The two-dimensional–three-dimensional (2D–3D) crossover point shifted upward in temperature. Conversely, to irradiation with low fluences (Φ ≤ 1019 e/cm2) or low praseodymium doping (z ≤ 0.39), irradiation with medium fluences or high praseodymium doping led to a non-monotonic dependence of ξc(0) on the irradiation fluence, with characteristic maxima at Φ~(7–8) × 1019 e/cm2 and z ≈ 0.42, likely due to the suppression of the superconducting characteristics.