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Using the methods of Auger electron spectroscopy, scanning electron microscopy, and measuring the angular dependences of the coefficient of inelastically reflected electrons, changes in the morphology, composition, and structure of CaF2 surface layers under electron bombardment with an energy of Ee = 1–8 keV are studied. The composition of the CaF2 surface changes noticeably at Ee = 2–3 keV and an electron dose of D ≥ 1018 cm–2. It is found that at a dose of less than 1018 cm–2, electrons are incident on separate sections of the CaF2 film. As D increases, the sizes of these sections increase, and starting from D = 8 × 1018 cm–2, the boundaries of neighboring sections overlap. The surface is completely covered with Ca atoms. After annealing at 900 K, a single-crystal Ca film is formed. At Ee = 3 keV, the thickness of the Ca film is ~25–30 Å. [ABSTRACT FROM AUTHOR]

In this work, we experimentally simulate the methanol (CH3OH) ice behavior (12 K) through the bombarded by fast electrons (4.9 keV) in an attempt to simulate radiation chemistry induced by radiation in space environments. The sample analysis by infrared spectroscopy reveals the appearance of new species, including CO2, CO, H2O, and CH4, during the sample bombardment. We have quantified the effective destruction cross-section of methanol (5.5 × 10-19 cm2) and determined the formation cross-section for these newly produced species. Additionally, we have characterized the chemical equilibrium (CE) phase, which becomes evident at higher fluences. We have also calculated molecular abundances and assessed the desorption yield induced by fast electrons within the same sample. Furthermore, we estimated the timescale required to achieve chemical equilibrium in specific astrophysical environments impacted by electrons. This study significantly contributes to our comprehension of electron bombardment behavior in astrophysical ices and allows for meaningful comparisons with organic-rich ices in space environments

Alterations in the structure of a magnetron, e.g., the A6 relativistic magnetron, are proposed, which considerably increase the device’s build-up speed. We cover the magnetron vane surfaces with semiconductor layers of nonzero electric conductivity, with an exact geometrical design. Semiconductor layers with considerable mechanical strength also provide excellent shielding for the vanes against the high-energy relativistic electrons’ bombardment. The novel structure introduces several new free parameters to the magnetron design procedure and considerably increases the design flexibility. A multistage exact optimization procedure, performed by extensive computer simulations, shows that applying silicon carbide layers with proper geometrical design doubles the build-up speed. In a general trend, we also indicate that adding semiconductor layers with nonzero electric conductivity to the magnetron vanes’ surfaces typically fastens the system by reducing the build-up transient time. It is verified that the insertion of conductivity to the vanes’ bodies with the proper design of shape and depth can increase the mode frequencies, build-up speed, and strength against electrons bombardment, saving the output amplitude. Finally, as shown by the simulation results data, the system behavior is analyzed theoretically. [ABSTRACT FROM AUTHOR]

Vacuum flat-panel detectors (VFPDs) using a cold cathode and photoconductor have important applications in large-area photodetectors; however, the mechanism for achieving high photoresponsivity must be further explored. In this article, theoretical analysis was performed to examine the electron-bombardment-induced photoconductivity (EBIPC) effect based on the equivalent circuit model. Formulas for photo/dark current were derived, which indicated that carrier multiplication was mainly due to energetic electron bombardment. The theoretical formulas also revealed the carrier multiplication mode inside the photoconductor of VFPDs and the relationship between the responsivity and device parameters. To verify the theoretical results, VFPDs with a ZnS photoconductor and ZnO nanowire cold cathode were studied. The responsivity initially increased and then decreased by increasing the photoconductor thickness. In addition, a broad dynamic range was achieved with a linear dynamic range of 106.02 dB, which was attributed to the efficient collection of carriers induced by EBIPC at the optimized thickness. Our theoretical results were validated by the experimental results and can provide guidance for developing VFPDs based on EBPIC. [ABSTRACT FROM AUTHOR]

Dynamic evolutions of morphology and size of swift heavy ion (SHI) induced latent tracks in muscovite mica were explored using in situ transmission electron microscopy (TEM) in this paper. Prior to the measurements, muscovite mica sheets were irradiated with Kr and Bi ions with electronic energy loss (d E /d x ) e of 5.9 keV/nm and 31.5 keV/nm, respectively. It is observed in TEM micrographs that the latent tracks in mica are continuously along the cross section view of the ion tracks. The track profile is not found dramatically uniform but rather it is found slightly fluctuating for similar (d E /d x ) e values. In situ TEM observation clarify that atoms in the track halo are unstable compared with the lattice atoms in the vicinity of the track. Point defects induced by the electron bombardment are generated preferentially around the track core, which results in the increased diameter of the track. [ABSTRACT FROM AUTHOR]

Ag-Mg alloy is used as a dynode material in electron multiplier tubes due to the high secondary electron yields (δ) of the surface of MgO film. However, MgO film is readily degraded under strong electron or ion bombardment, which results in a decrease in the lifetime of devices. In this study, alumina-containing MgO films of ~50-150 nm were developed on a Ag-2Mg-2Al alloy (silver alloy containing 2 wt % Mg and 2 wt % Al) after a thermal activation process performed at 500-600 °C under low oxygen pressures of 5.0-20.0 Pa. Auger electron spectroscopy and X-ray photoelectron spectroscopy analyses reveal that the film consists of a thin layer of pure MgO and a relatively thicker layer of alumina-containing MgO located beneath the top MgO layer. The alumina-containing MgO film exhibits high δ value of 7.7 at a primary electron energy of 580 eV and a much better stability under energetic electron bombardment than pure MgO film on Ag-Mg alloy. Alumina has higher bond dissociation energy than MgO, and the presence of alumina in the film contributes to mitigating the dissociation of the MgO film under electron bombardment. The Ag-2Mg-2Al alloy with alumina-containing MgO film is a promising candidate as a dynode material for electron multiplier tubes. [ABSTRACT FROM AUTHOR]

The electron induced effect on the first stages of the titanium (Ti0) oxidation and titanium dioxide (Ti4+) chemical reduction processes has been studied by means of Auger electron spectroscopy. Using factor analysis we found that both processes are characterized by the appearance of an intermediate Ti oxidation state, Ti2O3 (Ti3+).

[Display omitted] • UV photolysis of aniline in solid Ar. • Electron-bombardment of aniline in solid Ar. • IR absorption spectrum of anilino radicals in solid Ar. Electron bombardment of aniline (PhNH 2) in an Ar matrix mainly generated the aniline cation (PhNH 2 +), anilino (PhNH) and phenyl (Ph) radicals, and phenylnitrene (PhN). Further irradiation of the electron-bombarded matrix sample at 365 nm depleted PhNH 2 + and PhN, and resulted in the formation of PhNH 2 , PhNH, and Ph. In separate experiments, irradiation of the PhNH 2 /Ar matrix samples at 265 or 160 nm mainly generated PhNH and Ph radicals, but without the formation of PhNH 2 + and PhN. According to the observed photochemical behaviors, quantum-chemically predicted harmonic vibrational wavenumbers of each species, and the information reported in previous photodissociation studies, we unambiguously characterized the IR features of the aromatic species. The information of the vibrational fundamentals of PhNH is new and the formation mechanism is discussed. [ABSTRACT FROM AUTHOR]

The crystallinity of oxide phases strongly affects the properties of oxide coatings. In general, a well-crystallized oxide coating is desired because it usually results in improved mechanical and chemical properties. This paper presents a comparative study of the chromium oxide (Cr 2 O 3 ) coatings deposited by deep oscillation magnetron sputtering (DOMS), mid-frequency pulsed dc magnetron sputtering (PDCMS) and continuous dc magnetron sputtering (DCMS) without applying external substrate heating. The DOMS-Cr 2 O 3 coating deposition showed a peak substrate current density of 65 mA cm − 2 and a substrate saturation temperature of 250 °C, while the DCMS process exhibited a mean substrate current density of 1.29 mA cm − 2 and the lowest substrate saturation temperature of 212 °C. The sputtering techniques strongly affected the crystallinity of the Cr 2 O 3 coatings. The DCMS-Cr 2 O 3 coating exhibited an amorphous like structure. The PDCMS-Cr 2 O 3 coating contained a mixture of amorphous and crystalline α-Cr 2 O 3 phases. In contrast, the DOMS-Cr 2 O 3 coating showed a strong crystallinity with a (110) preferential orientation. The improved crystallinity of the DOMS-Cr 2 O 3 coating is attributed to the enhanced ion flux bombardment and a higher substrate saturation temperature, which is correlated to the energetic electron bombardment observed from the oscillatory substrate current. With the improved crystallinity, the DOMS-Cr 2 O 3 coatings exhibited significantly improved mechanical properties (a hardness of 35 GPa) and wear resistance (a dry coefficient of friction of 0.37 and a wear rate of 5.7 × 10 − 7 mm 3 N − 1 m − 1 ) as compared to the coatings deposited using DCMS and PDCMS. [ABSTRACT FROM AUTHOR]

A comparative analysis of the formation of radiation-induced defects in semiconductors (silicon and silicon carbide are used as examples) under bombardment with electrons with energies of 0.9 MeV or higher is carried out. Experimental values of the rate of charge-carrier removal at electron energies of 0.9 MeV are less by an order of magnitude than at higher electron energies (6-9 MeV). The formation cross section for primary radiation defects (Frenkel pairs) in this range is almost energy-independent. It is suggested that the reason for this difference is the influence of the energy of primary knocked-out atoms. As the energy of these atoms increases, first, the average distance between genetically related Frenkel pairs increases, and, as a consequence, the fraction of pairs that are not recombined under bombardment increases. Second, the possibility of forming new, more complex, secondary radiation effects appears as the energy of the primary knocked-out atoms increases. [ABSTRACT FROM AUTHOR]

We summarize an extensive study on the impact of absorber layer defect density on the performance of amorphous (a-Si:H) and microcrystalline (a-Si:H) silicon solar cells. To study the effects of the absorber layer defect density we subjected set of a-Si:H and a-Si:H cells to a 2 MeV electron bombardment. Subsequently the cells were stepwise annealed to vary the defect density. The cells have varying thicknesses and are illuminated from either the p- or n-side. For reference we subjected i-layers to the same treatment as the cells. The procedure enabled the reversible increase of the i-layer defect density (NS) with two orders of magnitude according to electron spin resonance measurements (ESR) performed on reference samples. The large variation of NS induces substantial changes in the current--voltage characteristics (J--V) and the external quantum efficiency spectra (EQE). These changes in device characteristics provide a solid reference for analysis and device simulations. It was found that performance of a-Si:H cells degraded weakly upon NS increase up to 1017 cm-3 and dropped steeply as defect density was increased further. In contrast, performance of µc-Si:H cells showed continuous reduction as NS raised. By comparing p- and n-side illuminated cells we found that, for NS above 1017 cm-3, the p-side illuminated a-Si:H cells outperformed the n-side illuminated ones, however, the difference was barely visible at NS below 1017 cm-3. On the contrary, the device performance of n-side illuminated µc-Si:H cells was much more affected by the increase in defect density, as compared to the p-side illuminated cells. EQE results evidenced a significant asymmetry in collection of electrons and holes in µc-Si:H devices, where carrier collection was limited by holes as defect density was increased. Based on the experimental data we speculate that the improvement of absorber material in terms of as-deposited defect density is not of primary importance for the performance of a-Si:H cells, whereas in ¿c-Si:H based solar cells, the reduction of the absorber layer defect density below the state-of-the-art levels, seems to improve the cell performance. [ABSTRACT FROM AUTHOR]

Abstract: This paper investigates the influence of a combined electron and ion bombardment via asymmetric bipolar pulsed substrate bias on the microstructure and mechanical properties of reactively magnetron-sputtered CrN hard coatings for two different ion-to-atom flux ratios. A short ratio of electron-to-ion bombardment duration leads to a preferred (110) orientation of the CrN phase, high residual stress up to −4.1GPa and hardness values up to 17.9GPa. An increased electron-to-ion bombardment ratio promotes a change in preferred orientation from (110) towards (100). Concurrently, residual stress and hardness values are reduced to a few ±100MPa and 15.1GPa, respectively. The texture cross-over from (110) to (100) is shifted to longer electron bombardment duration for higher ion-to-atom flux ratios. [Copyright &y& Elsevier]

Abstract: Nano-Fe powders could be prepared only after 10hours of ball milling assisted by dielectric barrier discharge (DBD), whose particle mean size was about 100nm. The synergetic refinement mechanism of DBD on ball milling had been investigated by examining the morphology of Fe powder using scanning electron microscopy and transmission electron microscope. It was shown through SEM that Fe particles displayed an extraordinary plasticity in the early assisted milling stages under the action of DBD, and the plastic deformation of Fe particles was more severe than that in normal milling. Large quantity of Fe particles about 50nm were observed by TEM which were generated during ball milling owing to the hot explosion effect caused by DBD electron bombardment. It was indicated that the refinement of Fe powder in DBD assisted ball milling could be promoted by the synergy effect of superplasticity, hot explosion and huge pulsating stress which were caused by the high-energy electron bombardment. [Copyright &y& Elsevier]

A physical model and program of calculating the parameters of charging dielectrics by electron bombardment is described. A method of computer simulation is used to investigate the main processes of charging the subsurface silicon dioxide layers. Dependences of the current density, volume charge density, and electric field strength on the material layer depth are calculated for variable electron beam parameters, irradiation time, and grid potential near the sample surface. [ABSTRACT FROM AUTHOR]

Abstract: Results of the studies on the effect of 8MeV electron beam irradiation of polystyrene substrates on the morphology of silver particulate films deposited at 455K in a vacuum of 8×10−6 Torr are reported. Optical absorption studies show the presence of transverse and longitudinal plasmon resonance for films deposited on irradiated polystyrene. Scanning electron microscopy reveals a decrease in particle size with smaller inter-particle separation for irradiated films. Larger clusters are formed in the case of films deposited on polystyrene after 300h of irradiation. In this paper, we show that the morphology of silver nanoparticulate films can be modified by electron irradiation of inert polymer substrates like polystyrene. The change observed due to irradiation is attributed to the formation of free radicals, thereby altering the polymer–metal interaction. [Copyright &y& Elsevier]

Abstract: We present an analysis of the dependence of the backscattering correction factor (BCF) in Auger-electron spectroscopy (AES) on the analyzer acceptance angle. Illustrative BCF calculations are presented for Pd M5N45N45 Auger electrons as a function of primary-electron energy for primary-electron angles of incidence, θ 0, of 0° and 80° and for various values of the analyzer acceptance angle. It was necessary to generalize the BCF definition for the case of an analyzer with an arbitrarily large acceptance angle; this was done with a new function, the integral emission depth distribution function. BCFs calculated from an advanced model of electron transport in the surface region of the Pd sample varied weakly with analyzer half-cone angle for θ 0 =0° but more strongly for θ 0 =80° where there were BCF differences varying between 19% at a primary energy of 1keV and 6% at a primary energy of 5keV. These BCF differences are due in part to variations of the BCF with emission angle and in part to variations of the density of inner-shell ionizations within the information depth for the detected Auger electrons. The latter variations are responsible for differences larger than 10% between BCFs from the widely used simplified BCF model and those from the more accurate advanced model for primary energies less than about 5keV for θ 0 =80°. For normal incidence of the primary beam, differences greater than 10% between BCFs from the simplified and advanced models were found for primary energies between 1keV and 4keV. These BCF differences indicate that the simplified model can provide only approximate BCF values. In addition, the simplified model does not provide any BCF dependence on Auger-electron emission angle or analyzer acceptance angle. [Copyright &y& Elsevier]