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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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Low-cost photodetector architectures fabricated at room-temperature using nano-engineered silicon wafer and sol-gel TiO2 – based heterostructures
摘要： In the last decades, significant research has been done on the nanocrystalline forms of titanium dioxide (tio2). Amorphous TiO2 has not been studied intensively despite being significantly less expensive compared to crystalline TiO2. This study reveals significant improvement in UV-VIS photodetection properties from heterostructures fabricated in ambient environment using n-type silicon nanowire arrays and amorphous TiO2 sol-gel. Our ultra-low-cost UV-VIS photodetectors can cover a wide range of applications. We report fast rise/decay time constants of 0.23 ms/0.17 ms and high responsivity up-to 6.0 A/W in the UV and 25.0 A/W in the visible range under low (1 V) external bias. The large surface area due to the nanowire array architecture leads to 2 orders of magnitude enhancement in photo-response. Besides the final electrode deposition, the entire device fabrication is performed using low-cost, all solution-based methods in ambient conditions. These low-cost UV-Visible broadband photodetectors can potentially serve a wide range of applications.
关键词： heterostructures,UV-VIS photodetection,TiO2,silicon nanowire,photodetector
更新于2025-09-11 14:15:04
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Sputtering yield measurements of laser ablated Mg-alloy correlated with surface, structural and mechanical modifications
摘要： Sputtering yield of laser ablated Mg-alloy has been measured by Quartz Crystal Microbalance at various fluences ranging from 11.6–44.2 J/cm2, under two different environments of Ar and O2. The sputtering yield initially increases from 14.58 × 1014 to 23.49 × 1014 and from 4.5 × 1014 to 22.60 × 1014 (atoms/pulse) by increasing fluence and then decreases upto a value of 19.78 × 1014 and 19.94 × 1014 (atoms/pulse) at the maximum fluence, under Ar and O2 environment respectively. Scanning Electron Microscope analysis reveals the formation of cones, cavities, droplets, ripples and island like structures on the irradiated Mg surface. Surface profilometry analysis reveals that the crater depth of laser irradiated Mg-alloy ranges from 188 to 209 μm. It initially increases by increasing laser fluence and afterwards, decreases at the maximum fluence. Energy Dispersive X-ray spectroscopy (EDX), X-Ray Diffraction analysis (XRD) and Ultraviolet-Visible (UV–vis) spectroscopy confirm the oxide formation for the laser treated target of Mg in O2. The Vickers Micro-hardness testing reveals that hardness of laser irradiated Mg-alloy is increased by increasing fluence. The surface structures, crater depth and hardness of laser irradiated Mg-alloy are strongly dependent upon laser fluence and are correlated with sputtering yield measurements.
关键词： UV–vis,EDX,XRD,Sputtering yield,Surface modifications,Crater depth,Mg-alloy AZ91D,Micro-hardness
更新于2025-09-11 14:15:04
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High-Performance Organic Photodetectors by Introducing a Non-Fullerene Acceptor to Broaden Long Wavelength Detective Spectrum
摘要： We demonstrate the broadband visible organic photodetectors (OPDs) by introducing a non-fullerene acceptor of 3,9-bis(2-methylene-(3-(1,1dicyanomethylene)-indanone))-5,5,11,11-tetrakis(4-hexylphenyl)-dithieno[2,3d:2,3′-d′]-s-indaceno[1,2-b:5,6-b′]dithiophene (ITIC) into the bulk heterojunction (BHJ) based on a conventional system of poly(3-hexylthiophene-2,5-diyl) (P3HT):[6,6]-phenyl C71-butyric acid methyl ester (PC71BM) .The resultant OPDs exhibit a specific detectivity beyond 1012 Jones in the whole visible region ranged from 380 nm to 760 nm, and the highest detectivity reaches 2.67 × 1012 Jones at 710 nm. UV-Vis absorption spectrum, steady-state photoluminescence, atomic force microscopy, and space-charge-limited current property were applied to analyze the film characteristics of obtained OPDs. Owing to the long-wavelength absorption band of ITIC, the spectral photodetection range has been broadened effectively, and better film morphology, more effective energy transfer, and the reduced electron mobility in the active layer are responsible for the excellent photodetection capability. The proposed scheme provides a reliable strategy for implementing high-performance broadband visible OPDs.
关键词： Organic photodetectors,UV-Vis absorption,Non-fullerene acceptor,Surface morphology,Full visible light photodetection
更新于2025-09-11 14:15:04
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Improved disinfection performance towards human adenoviruses using an efficient metal-free heterojunction in a vis-LED photocatalytic membrane reactor: Operation analysis and optimization
摘要： Waterborne human viruses, with ubiquitous prevalence in aquatic environments, extremely low infectious doses, and high resistance to common disinfection processes, pose a substantial threat to human health. Herein, for the first time, a photocatalytic membrane reactor (PMR) driven by visible light emitting diodes (Vis-LEDs) was applied for effective water disinfection of human adenoviruses. The photocatalyst used in the PMR was selected to be a metal-free heterojunction (named as CNO) with the advantages of visible-light-response, efficient virucidal effects, green properties and easy recovery via microfiltration. The disinfection performance of the Vis-LED PMR towards human adenoviruses was improved by adjusting operation with response surface methodology (RSM). Based on twenty sets of operating data, a semi-empirical model was established with a high accuracy of R2 = 0.9622 for predicting the final adenovirus inactivation after 300-min operation. The optimal operating solution was found to be 5.00-log MPN/mL, 320.30 mg/L and 502.65 min for initial virus concentration (IVC), photocatalyst loading (PL) and hydraulic retention time (HRT), respectively. Under the optimized operation, all human adenoviruses were completely inactivated without regrowth, accompanied by severe damage to capsids, within 600 min in the Vis-LED PMR. In addition, the CNO photocatalyst could be retained inside the reactor via low-energy microfiltration with excellent recovery (99.9 wt%) but without obvious chemical or structural changes. Our work can offer a simple, effective, economical and eco-friendly water disinfection device against resistant pathogenic microbes, with controllable efficiency by facilely varying operating solutions.
关键词： operation analysis,photocatalytic membrane reactor,Vis-LED,metal-free heterojunction,human adenoviruses,optimization
更新于2025-09-11 14:15:04
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Rapid synthesis of ZnO nanoparticles by waste thyme (Thymus vulgaris L.)
摘要： Synthesis of nanoparticles by utilizing microorganisms and plants in green methods is a feasible procedure. This method can be used instead of chemical procedures as an eco-friendly procedure. Antibacterial activity of zinc oxide nanoparticles as one of the best multifunctional nanoparticles is well known. In this study, ZnO nanoparticles were produced by waste thyme (Thymus vulgaris L.) extract. SEM, XRD, UV–Vis, visual analysis and FTIR spectroscopic techniques were used for characterizing ZnO nanoparticles. The absorption of wavelengths of the UV–Vis in the region of 290–320 nm confirmed the formation of zinc oxide nanoparticles. The average size of ZnO nanoparticles was estimated 10–35 nm by SEM technique. An eco-friendly method for the synthesis of ZnO nanoparticles can be used in which the waste thyme extract is used as a stabilizing agent. Therefore, the use of waste thyme extract is an alternative to the chemical methods. Biological methods are rapid, green, economical and simple to perform.
关键词： Medicinal plants,SEM,ZnO nanoparticles,UV–Vis,Green chemistry,XRD
更新于2025-09-11 14:15:04
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Stabilization of cubic phase in scandium-doped zirconia nanocrystals synthesized with sol-gel method
摘要： A new room-temperature synthesis of nanocrystals of scandium doped zirconium oxide by sol-gel method is reported. The structure of the obtained product is checked with standard structural analysis methods. The crystal phase of ZrO2-Sc2O3 nanocrystals changes from monoclinic to tetragonal and cubic with the increase in scandium concentration. The importance of the cubic phase, which appears at 10 mol% and refines at 16 mol% of Sc2O3 concentration, is emphasized. The UV-Vis absorption spectra of the product are measured, and its bandgap is evaluated from the fundamental absorption edge. The value of the bandgap was calculated as 5.65 eV for the cubic phase.
关键词： scandium-doped zirconia nanocrystals,UV-Vis spectra,sol-gel synthesis,stabilization of cubic phase
更新于2025-09-11 14:15:04
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The phenomenon of fluorescence in immunosensors
摘要： The phenomenon of fluorescence in immunosensors is described in this paper. Both structure and characteristics of biosensors and immunosensors are presented. Types of immunosensors and the response of bioreceptor layers to the reaction with analytes as well as measurements of electrochemical, piezoelectric and optical parameters in immunosensors are also presented. In addition, detection techniques used in studies of optical immunosensors based on light-matter interactions (absorbance, reflectance, dispersion, emission) such as: UV/VIS spectroscopy, reflectometric interference spectroscopy (RIfs), surface plasmon resonance (SPR), optical waveguide light-mode spectroscopy (OWLS), fluorescence spectroscopy. The phenomenon of fluorescence in immunosensors and standard configurations of immunoreactions between an antigen and an antibody (direct, competitive, sandwich, displacement) is described. Fluorescence parameters taken into account in analyses and fluorescence detection techniques used in research of immunosensors are presented. Examples of immunosensor applications are given.
关键词： absorbance,UV/Vis,fluorescence,immunosensor,biosensor
更新于2025-09-11 14:15:04
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Investigations on synthesis, growth and physicochemical properties of semi-organic nonlinear optical crystal: l-arginine sodium nitrate
摘要： Single crystals of l-arginine sodium nitrate semiorganic nonlinear optical crystal were grown by slow evaporation process at room temperature. The single crystal X-ray diffraction study confirms that the unit cell parameters of the grown l-arginine sodium nitrate crystal. Fourier transform infrared spectrum analysis was used to identify the functional groups of the grown crystal. The thermal stability of the l-arginine sodium nitrate was determined using thermogravimetric analysis and differential thermal analysis. The linear optical property of LARSN crystal has been studied using Ultraviolet–visible spectroscopy studies in the wavelength range 200–800 nm. The relative second harmonic efficiency of the l-arginine sodium nitrate compound is found to be 0.49 times that of Potassium Di-hydrogen phosphate. The mechanical property of the grown crystals was determined by Vicker’s micro hardness test and it proved the hard nature of the grown crystal. Dielectric study reveals that both dielectric constant and dielectric loss decreases with increase in frequency.
关键词： thermal analysis,l-arginine sodium nitrate,slow evaporation process,FTIR,nonlinear optical crystal,microhardness,dielectric properties,X-ray diffraction,SHG efficiency,UV–Vis spectroscopy
更新于2025-09-10 09:29:36
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UV-Vis spectroscopy
摘要： UV-Vis reflectance spectroscopy has been widely used as a non-invasive method for the study of cultural heritage materials for several decades. In particular, FORS, introduced in the 1980s, allows to acquire hundreds of reflectance spectra in situ in a short time, contributing to the identification of artist’s materials. More recently, microspectrofluorimetry has also been proposed as a powerful non-invasive method for the identification of dyes and lake pigments that provides high sensitivity and selectivity. In this chapter, the concepts behind these spectroscopic methodologies will be discussed, as well as the instrumentation and measurement modes used. Case studies related with different cultural heritage materials (paintings and manuscripts, textiles, carpets and tapestries, glass, metals, and minerals), which show the usefulness of UV-Vis reflectance spectroscopy and microspectrofluorimetry applied to the study of artworks, will also be presented.
关键词： glass,reflectance,microspectrofluorimetry,textiles,FORS,carpets and tapestries,paintings and manuscripts,minerals,non-invasive,metals,UV-Vis spectroscopy
更新于2025-09-10 09:29:36