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Single-step formation of Cr 2 N nanoparticles by pulsed laser irradiation
摘要： Chromium nitride nanoparticles with mean diameter distribution between 0.8 nm and 30 nm were produced by laser irradiation of a chromium target immersed in liquid nitrogen. Cr was directly converted to chromium nitride nanoparticles according to selected-area electron diffraction analyses using the transmission electron microscopy technique. Crystalline nanoparticles mostly consist of Cr2N, which is commonly reported together with the conversion of Cr2N to CrN and the mixture of chromium oxides. In addition, there is no evidence of oxidation by storage or photodegradation of the nanoparticles in isopropyl alcohol suspensions. The intensity profile of small-angle X-ray scattering indicates that the geometrical shape of the nanoparticles is not spherical but cylindrical with aspect ratio (height-to-radius) of 0:35–0:05. UV-Vis absorption spectroscopy reveals the presence of surface plasmon absorption at the ultraviolet region at wavelengths of 350, 372, and 397 nm. First-principles calculations of density of states, dielectric function, and optical conductivity performed within the theoretical framework of density functional theory for Cr2N with a hexagonal structure corroborate the formation of surface plasmons.
关键词： transmission electron microscopy,liquid nitrogen,chromium nitride nanoparticles,density functional theory,laser irradiation,UV-Vis absorption spectroscopy
更新于2025-09-11 14:15:04
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Theoretical and experimental study of artificially controlled backscattering fiber using femtosecond laser fabrication
摘要： Thirteen alloys including high- and low-strength nickel-base alloys, austenitic stainless steels, and ferritic alloys were irradiated using 2 MeV protons to a damage level of 2.5 dpa at 360 °C and assessed for their susceptibility to irradiation assisted stress corrosion cracking (IASCC) in both BWR normal water chemistry (NWC) and PWR primary water. Cracking susceptibility was highest for high strength nickel-base alloys, followed by the low strength nickel-base alloys and then the low strength iron-base alloys. Cracking in the nickel-based alloys was worst in normal water chemistry, which was reversed for the iron-based alloys. In general, cracking correlated with the degree of microstructure changes, though no single feature could be linked to cracking. IGSCC occurred in both the unirradiated and irradiated conditions in high strength nickel-base alloys with susceptibility being considerably higher following irradiation. In all cases, slip was planar, and the degree of slip localization correlated with the probability of IG crack initiation. Low strength nickel-base alloys showed the same dependence on environment as high strength alloys but were considerably less susceptible to IASCC initiation. Among the low strength iron-base alloys, alloy 800 was most susceptible to IASCC initiation in both BWR NWC and PWR primary water, which also correlated with grain boundary chromium depletion and silicon segregation. Across all alloys, cracking correlated with both the degree of localized deformation and the hardness in the irradiated condition. The agreement is expected as increased hardening also correlates with localized deformation, which is likely a necessary, though insufficient condition for cracking.
关键词： PWR primary water,Hardening,Irradiation assisted stress corrosion cracking,Radiation,BWR NWC,Structural materials
更新于2025-09-11 14:15:04
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Analysis of 1?MeV electron irradiation-induced performance degradation in the germanium bottom cell of triple-junction solar cells using temperature-dependent photoluminescence measurements
摘要： Temperature-dependent photoluminescence spectra of the germanium bottom cell of triple-junction solar cells unirradiated and irradiated with 1 MeV electrons were measured in the 10–300 K temperature range. In unirradiated germanium bottom cell, the spectra show that the PL intensity increases with temperature but slightly decreases at around 250 K because of the intrinsic defect. However, in irradiated germanium bottom cell, the spectra show that there are two negative thermal quenching processes (10–90 K and 200–270 K) and two usual thermal quenching processes (90–200 K and 270–300 K) as a result of the radiation-induced defects Ec (cid:1) 0.37 eV and Ec (cid:1) 0.12 eV.
关键词： Electron irradiation,germanium bottom cell,thermal quenching,temperature-dependent photoluminescence
更新于2025-09-11 14:15:04
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Pyrolysis‐Synthesized g‐C <sub/>3</sub> N <sub/>4</sub> /Nb <sub/>2</sub> O <sub/>5</sub> Nanocomposite for Enhanced Photocatalytic Activity under White LED Light Irradiation
摘要： The design and fabrication of highly active visible-light-driven photocatalysts have been received considerable attention in recent years. However, individual component-based photocatalysts are limited in their use because of the high recombination of photoinduced carriers and poor chemical stability. Herein, the Z-scheme-originated photocatalytic activity of in-situ deposited Nb2O5 NPs on the plane surface of carbon nitride (g-C3N4) nanosheets (i. e. CN-NbO) heterostructures was studied using a simple thermal pyrolysis method. The as-synthesized photocatalysts distinctly manifested efficient white light-emitting diode (LED) irradiation toward organic malachite green (MG) dye degradation and photocatalytic hydrogen generation. The CN-NbO heterostructure showed a faster degradation rate of the MG dye and a higher photocatalytic hydrogen evolution rate. In addition, the plausible Z-scheme photocatalytic mechanism for photocatalytic hydrogen production under LED light irradiation was discussed. Photoelectrochemcial studies showed that the superior photoactivity of CN-NbO heterostructure is mainly a result of the suitable alignment of the band edge positions, which diminish carrier recombination and facilitate efficient interfacial charge transport at their interface. This study provides an ideal method for in-situ fabrication of novel two dimensional/one dimension-based photocatalysts with high activity and stable performance for photocatalytic hydrogen generation.
关键词： Dye degradation,Hydrogen evolution,Nanoparticles,Photocatalyst,LED irradiation,Layered materials
更新于2025-09-11 14:15:04
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An analytical solution of the bioheat model in a spherical tissue due to laser irradiation
摘要： This article studies an analytical approach associated with Laplace transform, experimental temperature data and a sequential concept over time to obtain the thermal damage and the temperature in living tissue due to laser irradiation. The effects of blood perfusion and the thermal relaxation time on the temperature of skin tissues and the resulting of thermal damage are investigated. The resulting of thermal damage to the tissue is assessed by the denatured protein range using the formulation of Arrhenius. The outcomes show that the hyperbolic bioheat model is reduced to the parabolic bioheat model when the relaxation time is close to zero. The numerical outcomes of thermal injuries and temperatures are graphically introduced. In conclusion, the comparison between the numerical computations and the existing experimental study displays that a current mathematical model is an effective tool for evaluating the biological heat transfer in biological tissues.
关键词： Laser irradiation,Laplace transforms,Thermal damages,Skin tissues
更新于2025-09-11 14:15:04
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Influence of Pulsed He–Ne Laser Irradiation on the Red Blood Cell Interaction Studied by Optical Tweezers
摘要： Optical Tweezers (OT), as a revolutionary innovation in laser physics, has been extremely useful in studying cell interaction dynamics at a single-cell level. The reversible aggregation process of red blood cells (RBCs) has an important in?uence on blood rheological properties, but the underlying mechanism has not been fully understood. The regulating effects of low-level laser irradiation on blood rheological properties have been reported. However, the in?uence of pulsed laser irradiation, and the origin of laser irradiation effects on the interaction between RBCs remain unclear. In this study, RBC interaction was assessed in detail with OT. The effects of both continuous and pulsed low-level He–Ne laser irradiation on RBC aggregation was investigated within a short irradiation period (up to 300 s). The results indicate stronger intercellular interaction between RBCs in the enforced disaggregation process, and both the cell contact time and the initial contact area between two RBCs showed an impact on the measured disaggregation force. Meanwhile, the RBC aggregation force that was independent to measurement conditions decreased after a short time of pulsed He–Ne laser irradiation. These results provide new insights into the understanding of the RBC interaction mechanism and laser irradiation effects on blood properties.
关键词： red blood cells (RBCs),Helium–Neon laser,laser irradiation,optical tweezers,RBCs interactions
更新于2025-09-11 14:15:04
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Enhanced activity of β-Ga2O3 by substitution with transition metal for CO2 photoreduction under visible light irradiation
摘要： Gallium oxide semiconductors have been developed as effective photocatalysts for water splitting driven by UV light irradiation, but there is no relevant study for the CO2 photoreduction application. Herein, we report the first investigation of β-Ga2O3 applying to photocatalytic CO2 reduction under visible light irradiation by doping transition metal ions (M = V, Cr, Mn, Fe, Co, Ni and Cu) onto the framework. Using sol-gel method, a series of transition metal ions incorporated β-Ga2O3 have been successfully obtained, in which the transition metal substitution content is 2 mol %. The β-Ga2O3:M photocatalysts are characterized completely by diverse tests (e.g., XRD, XPS, UV-Vis DRS, SEM). The effective replacement of Ga3+ ion by M ions significantly expands the scope of spectral response from UV light to visible light, and Fe3+, Co2+, Ni2+ significantly enhance the photocatalytic activity under visible light irradiation. In these cases, CO and H2 are evolved as the reduction products from CO2 and H+ by the generated electrons, respectively. Among these effective catalysts we prepared, β-Ga2O3:Ni exhibits the most substantial CO formation rate of 14.3 μmol/h at 30 °C, and the selectivity for CO evolution exceeds 60.9 %. Furthermore, the CO formation rate increases to 24.6 μmol/h after loading of Ag as the co-catalyst. The stability of the Ag/β-Ga2O3:Ni are verified after five cycle of CO2 photoreduction under visible light.
关键词： transition metal substituted,visible light irradiation,CO2 photoreduction,gallium oxide
更新于2025-09-10 09:29:36
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Effect of Biphenyl conjugation on the photosensitive properties of liquid crystalline polymers”
摘要： A series of side-chain liquid crystalline photosensitive polymers with pendent chalcone moiety were synthesized. The structure of the thermotropic, novel liquid crystalline photosensitive monomers and polymers was confirmed by IR, 1H - and 13C- NMR and UV visible spectroscopic techniques. The molecular weight of the polymers was determined by gel permeation chromatography. The photo-crosslinking properties of these polymers were studied by ultraviolet spectroscopy. The crosslinking proceeds via 2π+2π cycloaddition reaction of the styryl unit. The rate of crosslinking increased with increase in methylene chain length of the polymer. The thermal stability of the polymers was assessed by thermogravimetric analysis (TGA). The phase behavior and mesomorphism of the polymers were investigated by differential scanning calorimetry, X-ray diffraction and polarizing optical microscopy. The polymers exhibited nematic phase in hot stage optical polarized microscope (HOPM).
关键词： Chalcone,Thermal stability,Nematic phase,Mesophase,UV irradiation,Liquid crystalline polymer
更新于2025-09-10 09:29:36
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A study of 8 MeV e-beam on localized defect states in ZnO nanostructures and its role on Photoluminescence and third harmonic generation
摘要： In this article we have explored an effect of electron beam irradiation (EBI) on physical and nonlinear optical properties ZnO thin nano films. Nanostructured ZnO thin films were grown by low cost spray pyrolysis technique. The irradiation dosage has been fixed at 5kGy, 10kGY, 15kGy and 20kGy. The structural investigation by Glancing angle X-Ray Diffractometer (GAXRD) confirms a polycrystalline phase of ZnO with wurtzite structure. The variation in the surface morphology upon EBI has been demonstrated using 2D and 3D Atomic force microscopy (AFM) images. Nanoscope software analysis quantifies the variation in surface roughness and average particle height upon EBI. The defect states created in the films upon irradiation experiments were investigated using UV- visible spectrophotometer, Room temperature Photoluminescence (RTPL), Raman and X-ray photoelectron spectroscopy (XPS). The increase in urbach tail validates the creation of localized defect states in the films The Gaussian fitting on RTPL spectra shows the quenching in the luminescent centers upon irradiation arised as result of recombination of vacancy defects. Phonon confinement model fitting on Raman spectra endorses that shift in the phonon modes observed on irradiation is due to spatial confinement of phonons. The elemental composition and impurity states of the EBI ZnO thin films were studied using XPS spectra. The shift in the binding energy of Zn and O elements infers the electron beam induced changes in the films. The electron beam irradiation has resulted in the increment of third order optical susceptibility χ(3) from 3.5×10-4esu to 8.13×10-3esu due to the enhancement of electronic transition to different defect levels formed in the films and through local heating effects arising due to continuous wave (CW) laser illumination. The enhanced THG signal investigated using Nd:YAG laser at 1064nm and 8 ns pulse width shows the promising features of EBI ZnO films for frequency tripling applications.
关键词： Electron beam irradiation,Phonon confinement model,third harmonic generation,ZnO nanostructures,Localized defect states
更新于2025-09-10 09:29:36
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Evaluation of sensitivity of Ge9As9Se82 and Ge16As24Se60 thin films to irradiation with electron beam
摘要： The interaction of Ge9As9Se82 and Ge16As24Se60 amorphous chalcogenide thin films with electron beam has been investigated. The kinetics of surface relief formation was determined for both film compositions. It was established that for identical electron beam irradiation parameters, the kinetics of relief formation can be correlated with charge accumulation rate, its final value inside films and charge diffusion away from the electron interaction region. Charge model has been used to explain various phenomena during electron beam interaction with studied systems and parameters of this model are determined. Application of studied systems in single stage electron beam lithography is also presented.
关键词： Surface potential,Electron beam irradiation,Chalcogenide thin films,Ge-As-Se
更新于2025-09-10 09:29:36