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Speciation and Determination of Ionic and Trace-Level Colloidal Silver in Selected Personal Care Products by Thermal Lens Spectrometry
摘要： The collinear dual beam thermal lens spectrometric (TLS) detection in batch mode (BM), as well as combined with the flow injection analysis (FIA), was applied to determine the colloidal silver in personal care products available in the public pharmacies and declared by producers to contain nanosilver at the level of 5-30 μg ml-1. It was found, that the examined samples contain mainly ionic silver (99% or more), whereas the colloidal form of silver is at the level of less than 1 μg ml-1. The TLS methods were confirmed to be fast, precise, highly accurate and highly sensitive with limits of quantitation of 0.30 ng ml-1 and 1.50 ng ml-1 and relative standard deviations not higher than 1.2% and 6.0% for BM- and FIA-TLS configuration, respectively. The developed TLS methods have nearly 60 times lower LOQ values concerning the colloidal silver determination than the classical spectrophotometric method. To verify the obtained results of the real sample analysis the total amount of ionic silver was determined by the use of ICP-OES technique.
关键词： Thermal lens spectrometric determination,Personal care products,Flow injection analysis,Silver nanoparticles,Colloidal silver
更新于2025-09-23 15:21:21
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Green Synthesis of Silver Nanoparticles Contained in Centrifuged Citrus Oil and Their Thermal Diffusivity Study by Using Thermal Lens Technique
摘要： Thermal lens spectrometry is a very sensitive non-evasive technique that offers a reliable alternative for measurement of materials thermal diffusivity. In this work, silver nanoparticles from leaf extract of Azadirachta Indica (neem) and silver nitrate were synthesized using reverse micelle microemulsion. The thermal lens technique was used to obtain the thermal diffusivity of silver nanoparticles emulsions contained in grapefruit centrifuged oil. Thermal diffusivity of silver nanoparticles was measured as a function of concentration. The results showed an increase in the thermal diffusivity of the nanoemulsion with the increase in nanoparticle concentration. Also, the nanoemulsion exhibited improved thermal diffusivity in comparison with the base fluid. Transmission electron microscopy was used to determine the morphology of the nanoparticles. Results showed that they were spherical in shape with an average size of 35 nm. UV–Vis spectrometry was used to observe the absorption spectra of nanoparticles plasmon. This study has future applications in dermatological therapies against allergies, in tissue regeneration and in the cosmetic area, due to silver nanoparticles antibacterial properties.
关键词： Thermal diffusivity,Nanoparticles,Colloids,Thermal lens
更新于2025-09-23 15:21:01
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High-power operation of double-pass pumped Nd:YVO <sub/>4</sub> thin disk laser
摘要： A simple, compact, double-pass pumped Nd:YVO4 thin disk laser is demonstrated. Its continuous-wave performance with different Nd doping concentrations and thicknesses is investigated experimentally. The maximum output power of 17.7 W is achieved by employing a 0.5 at.% doped sample, corresponding to an optical-to-optical ef?ciency of 46% with respect to the absorbed pump power. In addition, a numerical analysis and an experimental study of the temperature distribution, and thermal lens effect of the Nd:YVO4 thin disk, are presented considering the in?uence of the energy transfer upconversion effect and the temperature dependence of the thermal conductivity tensor. The simulated results are in good agreement with the experimental results.
关键词： energy transfer upconversion effect,Nd:YVO4,thin disk laser,thermal lens effect
更新于2025-09-23 15:19:57
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Enhanced thermal diffusivity of water in the presence of iron oxide nanoparticles: a laser induced thermal lens measurement
摘要： Iron oxide nanoparticles are prepared using co-precipitation method and its thermal diffusivity as a function of concentration in distilled water is measured using laser induced thermal lens technique. The morphology, distribution and particle size are determined using SEM measurements. The elemental composition and optical properties of the sample are obtained from EDAX and UV–visible absorption spectra. It is found that the thermal diffusivity of the nanoparticle solution is larger than that of pure water at low concentrations but it is decreasing with increase in concentration of the nanoparticles. Variation of electrical conductivity and magnetic susceptibility of the same sample are also studied.
关键词： thermal lens,iron oxide nanoparticles,thermal diffusivity
更新于2025-09-16 10:30:52
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Optical and Thermal Properties of Laser-Ablated Platinum Nanoparticles Graphene Oxide Composite
摘要： Platinum nanoparticles were synthesized in graphene oxide aqueous solution using a laser ablation technique to investigate the effect of optical linear, nonlinear and thermal properties of platinum-graphene oxide nanocomposite solution. The samples were prepared with different ablation times. The platinum nanoparticles that formed a spherical shape on the surface of graphene oxide solution were authenticated using UV-visible spectrum and transmission electron microscopy patterns. The particle size decreased with increasing ablation time, and the concentration and volume fraction of samples were increased. To obtain the optical linear, nonlinear and thermal properties of platinum-graphene oxide nanocomposite solution, UV-visible spectroscopy, Z-scan, thermal lens and photoacoustic techniques were used. Consequently, the linear and nonlinear refractive indices increased with an increase in the volume fraction of platinum nanoparticles. It was observed from the spatial self-phase modulation patterns that, the optical nonlinear property of the graphene oxide was enhanced in the presence of platinum nanoparticles, and the nonlinearity increased with an increase in the volume fraction of platinum nanoparticles inside the graphene oxide solution. The thermal diffusivity and thermal effusivity of platinum nanoparticles graphene oxide were measured using a thermal lens and photoacoustic methods, respectively. The thermal diffusivity and thermal effusivity of samples were in the range of 0.0341 × 10?5 m2/s to 0.1223 × 10?5 m2/s and 0.163 W s1/2 cm?2 K?1 to 0.3192 W s1/2 cm?2 K?1, respectively. Consequently, the platinum enhanced the optical and thermal properties of graphene oxide.
关键词： graphene oxide,z-scan,spatial self-phase modulation,Pt-NPs,platinum nanoparticles/graphene oxide composite,laser ablation,photoacoustic,thermal lens
更新于2025-09-16 10:30:52
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[IEEE 2019 IEEE High Power Diode Lasers and Systems Conference (HPD) - Coventry, United Kingdom (2019.10.9-2019.10.10)] 2019 IEEE High Power Diode Lasers and Systems Conference (HPD) - Simulation of the slow-axis beam properties of broad-area lasers and its use in the development of high-brightness sources
摘要： The objective of this work is to demonstrate that the slow-axis beam properties of broad-area diode lasers can be predicted by numerical modeling and that the results guide design decisions in the semiconductor laser development. We present a numerical study for 6 different semiconductor laser single emitter designs and compare the computed results to experimental values. The devices differ in width of the contact opening, cavity length, position and depth of an index trench, and facet re?ectivity.
关键词： Semiconductor Lasers,Index-Guided,Beam Propagation Method,Lasers,Modeling,Gain-Guided,Frequency Domain,Simulation,Thermal Lens,Diode Lasers,Broad-Area
更新于2025-09-16 10:30:52
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Application of thermal lens microscopy (TLM) for measurement of Cr(VI) traces in wastewater
摘要： In this work, we demonstrate for the ?rst time that Thermal Lens Microscopy technique (TLM) can be applied to monitor the dynamics of a photocatalytic process in-situ. The photocatalytic reduction of hexavalent chromium -Cr(VI)- in aqueous solution using CdS and irradiated with visible light is monitored by TLM. Since the values of Cr(VI) concentration obtained after the photocatalytic process were close to those imposed by the international regulations for drinking water, the use of TLM allowed its measurement with a better reliability than with UV spectroscopy, usually used in this kind of analysis.
关键词： Cr(VI),Photocatalysis,Photoreduction,Thermal lens microscopy,Photothermal,CdS photocatalyst
更新于2025-09-10 09:29:36
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Thermal lensing measurements of Ti: Sapphire crystal pumped at 80?MHz picosecond pulses by Shack-Hartmann wavefront sensor
摘要： The thermal lensing effects in the lasing crystal appear to be dominant when the pump laser focused on the lasing crystal which causes the local heating effect. The spatial refractive index variations observed if the crystal has non-uniform temperature distribution. In the present study, the demonstration of thermal lensing effect of Brewster-cut Ti: Sapphire crystal carried out when pumped by 25 ps pulses at 80 MHz repetition rate with 532 nm central wavelength, while the average pump power controlled by the attenuator. The thermal lensing effects measured first at the ～293 K temperature and later at ～40 K by using the cryogenic cooling system. The thermal lensing variations at different average pump power were calculated and measured by using the HASO4 Shack-Hartmann wavefront sensor.
关键词： Thermal lens,Cryogenic cooling,Ti: Sapphire crystal,Shack-Hartmann wavefront sensor
更新于2025-09-10 09:29:36
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On the efficient Te4+→Yb3+ cooperative energy transfer mechanism in tellurite glasses: A potential material for luminescent solar concentrators
摘要： Te4+/Yb3+ co-doped 80%TeO2-20%Li2O glasses (amounts in mol%) were prepared by the conventional melt-quenching method in an ambient atmosphere, in order to investigate their optical characteristics for application in solar cells. An efficient near-infrared down-conversion mechanism was observed in these samples, involving the emission of two near infrared photons (at around 978 nm) after the absorption of one photon in the ultraviolet-blue region. This effect occurred by means of a process of cooperative energy transfer (CET) from Te4+ to Yb3+ ions. The CET efficiency (h CET) was calculated from radiative transitions (lifetime) and also by a new method, developed in this work, based on rate equations quantifying the non-radiative transitions (thermal effect) involved in the system. The two methods showed very good agreement, with h CET between 82-100% obtained for the sample prepared using a higher Yb3+ concentration (4 mol%). The results suggested that these tellurite materials could have potential applications in improving the efficiency of silicon-based solar cells.
关键词： Te4+ ions,Thermal lens effect,Tellurite glass,Yb3+ ions,Down-conversion,Cooperative energy transfer
更新于2025-09-09 09:28:46