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Electrochemical behaviour and analytical applications of a manganese porphyrin a?? silica hybrid film prepared by pulsed laser deposition
摘要： Hybrid nanomaterials can have superior properties in comparison with individual components, sometimes greatly improving their optoelectronic activity. For this reason, modified carbon electrodes were obtained using a hybrid material composed of 5,10,15,20-tetra(4-tolyl)porphyrinato manganese (III) chloride (MnTTP) embedded in a silica matrix. The laser ablation deposition technique (PLD) has been used to immobilize the manganese porphyrin–silica hybrid on the surface of the carbon electrodes. The successful transfer of the manganese-porphyrin was evidenced by UV–Vis absorption spectroscopy. The PLD-deposited hybrid film was characterized using AFM and electrochemical methods (cyclic voltammetry and square wave voltammetry). The viability of this hybrid nanomaterial film as a redox mediator for the anodic oxidation and sensitive voltammetric determination of ascorbic acid in buffer solution (pH = 6.5) is described. The recorded anodic process is attributed to its oxidation to dehydroascorbic acid, with satisfactory catalytic current response and low non-Faradaic current.
关键词： Mn-porphyrin,Silica matrix,Hybrid nanomaterial,Pulse laser deposition,Electrocatalytic film,Ascorbic acid
更新于2025-09-19 17:13:59
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Research of the Structure Defects at Wire-Feed Laser and Laser-Arc Deposition with AlMg6
摘要： In comparison with other additive methods, the wire additive manufacturing has some advantages, chief among: high deposition rate and low price for consumables. Otherwise there are some disadvantages such as a high level of internal defects (hot, cold cracks, pores). Adding laser radiation to a WAAM process can significantly reduce data flaws. In this paper outlined research results on the effect of laser radiation (pulsed and permanent) on structure and internal defects of deposit layers to create three-component structures from AlMg6 alloy. Reported samples was made by using hybrid laser-arc method and by applying a single laser. Presented photos of macrosections of obtained samples. Spectral analysis was performed to identify the nature of changes of grains in different processes. Were made the measurements of internal defects and chemical analysis of the obtained walls.
关键词： MIG torch,СW laser mode,wire and laser additive manufacturing,pulse laser mode,hybrid laser arc technology
更新于2025-09-16 10:30:52
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X-ray radiation protection aspects during ultrashort laser processing
摘要： Ultrashort pulse laser processing of materials allows for precise machining with high accuracy. By increasing the repetition rate to several 100 kHz, laser machining becomes quick and cost-effective. Ultrafast laser processing at high repetition rates and peak intensities above 1013 W/cm2 can cause a potential hazard by generation of unwanted x-ray radiation. Therefore, radiation protection must be considered. For 925 fs pulse duration at a center wavelength of 1030 nm, the x-ray emission in air at a repetition rate of 400 kHz was investigated up to a peak intensity of 2.6 × 1014 W/cm2. Based on the presented measurements, the properties of potential shielding materials will be discussed. By extending our previous works, a scaling of the x-ray radiation emission to higher peak intensities up to 1015 W/cm2 is described, and emitted x-ray doses are predicted.
关键词： laser-induced x-ray emission,ultrashort pulse laser processing,laser ablation,radiation protection
更新于2025-09-16 10:30:52
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Near-Surface Plasma Formed by Dual-Pulse Laser Action at Two Wavelengths on Titanium in Air
摘要： Spectra and structures of near-surface plasma torches were studied experimentally by measuring the speci? c mass loss and plume luminosity caused by dual-pulse laser radiation at wavelengths 1064 and 532 nm on titanium in air as functions of the time between laser pulses and their sequence. Dependences of the laser-plasma temperature and concentration of charged particles on the paired laser pulse parameters were established at laser radiation power densities q1064 ≤ 3.1·109 and q532 ≤ 2.7·109 W/cm2 for λ = 1064 and 532 nm. The optimal conditions for recording erosion plasma spectra had the initial effect from second-harmonic radiation with a time interval between pulses of 4–5 μs; for speci? c mass loss, 3–6 μs. The results were important for enhancing the ef? ciency of laser emission spectral analysis and laser-plasma processing of materials.
关键词： speci? c mass loss,laser plasma,plasma-torch structure,plasma temperature,electron concentration,dual-pulse laser action
更新于2025-09-16 10:30:52
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Effect of laser texturing on the performance of ultra-hard single-point cutting tools
摘要： This paper investigates the cutting performance and anti-adhesive properties of textured single-point polycrystalline diamond (PCD) cutting tools in machining Aluminium 6082 alloys. The micro/nano textures were first milled using a fibre laser (1064-nm wavelength) at different power intensities, feed speeds and pulse durations, and finally characterised using scanning electron microscopy, white light interferometry and energy dispersive X-ray spectroscopy. The effect of different textures on the cutting performance was investigated in turning tests under dry cutting conditions. The test was stopped at regular lengths of cut to allow analysis of height of adhesion through 3D white light interferometry. The data processing of the cutting forces and the microscopical characterisation of the tested cutting tools enabled the evaluation of the effects of texture design, friction coefficient and adhesive properties. The results indicated that feed force in tools with grooves perpendicular to the chip flow direction (CFD) was more stable (20–40 N) than the benchmark (6–41 N). Similarly, the thrust force for tools with grooves parallel to CFD and grooves perpendicular to CFD showed a homogeneous trend fluctuating between 60 and 75 N as compared with the benchmark (ranging between 73 and 90 N). For texture depth in the order of 260 nm and post process roughness in the order of tens of nanometers, a reduction of average friction coefficient (0.28 ± 0.14) was reported when using lasered inserts with grooves parallel to the chip flow direction compared with the benchmark tools (0.34 ± 0.26) corroborated by reduced stiction of workpiece material on the rake face. In machining via textured tools with grooves perpendicular to CFD, the cutting forces were reduced by 23%, and the surface quality of the machined workpiece was improved by 11.8%, making this geometry the preferred choice for finishing applications. Using grooves parallel to CFD reduced the cutting forces by 11.76%, adhesion by 59.36% and friction coefficient by 14.28%; however, it increased the surface roughness of the machined workpiece, making this geometry suitable for roughing operations. For the first time, laser manufacturing is proposed as a flexible technique to functionalise the geometrical and wear properties of PCD cutting tools to the specific applications (i.e. roughing, finishing) as opposed to the standard industrial approach to use microstructurally different PCDs (i.e. grain size and binder %) based on the type of operation.
关键词： Adhesion,Dry cutting,Nanosecond pulse,Laser milling,Polycrystalline diamond insert,Laser surface texturing,Cutting forces
更新于2025-09-16 10:30:52
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Femtosecond Pulsed Laser Deposition of Chromium Diboride-Rich Thin Films
摘要： Chromium borides are promising candidates for several structural applications including protective coatings for materials exposed to corrosive and abrasive environments. In this paper the pulsed laser deposition of chromium diboride-rich thin ?lms has been carried out in vacuum by using a frequency doubled Nd:glass laser with a pulse duration of 250 fs. The ?lms have been deposited at di?erent substrate temperatures and characterized by X-ray di?raction, X-ray photoelectron spectroscopy, scanning electron microscopy and transmission electron microscopy. Lastly, the ?lm’s hardness has been studied by Vickers indentation technique. The results indicate that only the ?lms deposited at a substrate temperature of 500 C are crystalline and formed by chromium diboride, together with a certain amount of boron and chromium, which suggests that, as main mechanism, a process taking place on the surface from atoms and ions from the gas phase. This hypothesis has been con?rmed by the study of the plasma produced by the ablation process.
关键词： thin ?lms,pulsed laser deposition,chromium diboride,ultra-short pulse laser
更新于2025-09-16 10:30:52
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Optimization of laser parameters for proton acceleration using double laser pulses in TNSA mechanism
摘要： The energy of protons accelerated by ultra-intense lasers in the target normal sheath acceleration (TNSA) mechanism can be greatly enhanced by the laser parameter optimization. We propose to investigate the optimization of laser parameters for proton acceleration using double laser pulses in TNSA mechanism. The sheath field generation at the rear side of the target is significantly affected by the introduction of second laser pulse in TNSA mechanism, and consequently, the energy of the accelerated protons is also modified. The second laser pulse was introduced with different delays to study its impact on proton acceleration. Our study shows that the interplay of laser intensity and pulse duration of both laser pulses affects the proton acceleration. It was found that the proton maximum energy is the function of both laser intensity and pulse duration. A number of simulations have been performed to obtain maximum proton energy data under different combinations of laser intensity and pulse duration for the two laser pulses. The simulation results account for the underline physics for the proton bunch energy and the sheath field as a function of pulse intensity and pulse delay.
关键词： proton acceleration,ultrashort laser pulse,Laser–plasma interaction
更新于2025-09-16 10:30:52
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Numerical simulation of millisecond laser-induced output current in silicon-based positive-intrinsic-negative photodiode
摘要： Based on the photoelectric e?ect, the output current model of the silicon-based positive-intrinsic-negative (PIN) photodiode irradiated by millisecond pulse laser was established; the time distribution of the output current on the PIN photodiode under di?erent bias voltages, energy densities, and pulse widths were calculated. The results showed that: the output current process of PIN photodiode irradiated by millisecond laser could be divided into three stages: photo-generated current stage, conduction stage and recovery stage; at the photo-generated current stage, the peak value of output current increased with the increase of energy density and bias voltage; at the conduction stage, with the increase of energy density the value of output current remained the same while increased with the increase of bias voltage; at the recovery stage, with the increase of bias voltage the value of recovery time remained the same while increased with the increase of energy density. In this paper, the simulation results were consistent with the experiment results.
关键词： Numerical simulation,Output current,Millisecond pulse laser,Photodiode
更新于2025-09-16 10:30:52
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[IEEE 2019 18th International Conference on Optical Communications and Networks (ICOCN) - Huangshan, China (2019.8.5-2019.8.8)] 2019 18th International Conference on Optical Communications and Networks (ICOCN) - Black Phosphorus Based Ultrafast Yb-doped Fiber Laser: Principle, Mechanisms, and Applications
摘要： Since early 2014, black phosphorus (BP), a rising star among post-graphene, has been exploited to generate ultrashort pulses in fiber lasers. BP has a large direct bandgap range from 0.3 eV (bulk, corresponding to 4.13 μm) to 2 eV (monolayer, corresponding to 620 nm), which enables ultrashort pulse generation from near-infrared to visible waveband. In our progresses, an ultra-stable (more than 100 days) pulse fiber laser based on real BP-SA was demonstrated, which exhibited various interesting ultrafast phenomenon in 1 μm region. Our results extended the application of BP in the spatial and temporal domains.
关键词： pulse laser,black phosphorus,saturable absorber
更新于2025-09-16 10:30:52
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AIP Conference Proceedings [AIP Publishing INTERNATIONAL CONFERENCE ON SCIENCE AND APPLIED SCIENCE (ICSAS) 2019 - Surakarta, Indonesia (20 July 2019)] INTERNATIONAL CONFERENCE ON SCIENCE AND APPLIED SCIENCE (ICSAS) 2019 - Effect of solvent in the synthesis of colloidal copper nanoparticles by pulse laser ablation method
摘要： Effect of solvent in the synthesis of colloidal copper nanoparticles by pulse laser ablation method
关键词： pulse laser ablation,solvent effect,colloidal copper nanoparticles
更新于2025-09-16 10:30:52