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Investigating double pulse nanoparticle enhanced laser induced breakdown spectroscopy
摘要： Several strategies have been e?ectively tested in the past to improve the Laser Induced Breakdown Spectroscopy (LIBS) signal, involving peculiar experimental con?gurations, such as Double Pulse LIBS (DP-LIBS). Recently, sample treatment has proven to be a viable and simple way to enhance the LIBS performances; in particular, the Nanoparticle-Enhanced LIBS (NELIBS) methodology uses a deposition of metal nanoparticles (NPs) on the sample to greatly increase the emission of the LIBS plasma. In this work, we investigate the possibility of combining, for the ?rst time, DP-LIBS with NELIBS. The chosen set-up uses two parallel non-collinear laser pulses to ensure the activation of NPs during both pulses, while maintaining the low-pressure environment typical of DP-LIBS. The two laser beams are spatially separated so that the second beam is focused within the shock wave generated by the ?rst one. This con?guration allows the exploitation of the combined enhancement of both DP-LIBS and NELIBS. Several tests on copper targets have been performed to determine the best set-up for the maximum magnitude of the signal enhancement by adjusting di?erent parameters such as pulse energies and o?set distances. Commercially available silver NPs and NPs prepared by pulsed laser ablation in liquid have been tested and their performances compared with standard DP-LIBS.
关键词： Pulsed laser ablation in liquids,Double pulse LIBS,Nanoparticle enhanced LIBS,Spatially o?set DP-NELIBS,Signal enhancement
更新于2025-09-19 17:13:59
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Development of ZnO Nanoparticles as an Efficient Zn Fertilizer: Using Synchrotron-Based Techniques and Laser Ablation to Examine Elemental Distribution in Wheat Grain
摘要： Zinc (Zn) deficiency is an important problem worldwide, adversely impacting human health. Using a field trial in China, we compared the foliar-application of both ZnO nanoparticles (ZnO-NPs) and ZnSO4 on winter wheat (Triticum aestivum L.) for increasing the Zn concentration within the grain. We also used synchrotron-based X-ray fluorescence microscopy (μ-XRF) and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) to examine the distribution of Zn within the grain. We found that ZnO-NPs increase the Zn concentration in the wheat grain, increasing from 18 mg·kg-1 in the control up to 40 mg·kg-1 when the ZnO-NPs were applied four times. These grain Zn concentrations in the ZnO-NP-treated grains are similar to those recommended for human consumption. However, the ZnO-NPs were similar in their effectiveness to ZnSO4. When examining trace element distribution in the grain, the trace elements were found to accumulate primarily in the aleurone layer and the crease region across all treatments. Importantly, Zn concentrations in the grain endosperm increased by nearly 30-fold relative to the control, with this markedly increasing Zn within the edible portion. These results demonstrate that ZnO-NPs is a suitable fertilizer for increasing Zn within wheat grain and can potentially be used to improve human nutrition.
关键词： X-ray fluorescence microscopy (μ-XRF),foliar application,wheat,Zn biofortification,laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS),ZnO-NPs
更新于2025-09-19 17:13:59
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Single‐Fiber Laser Ablation in Treating Selected Metastatic Lymph Nodes of Papillary Thyroid Carcinoma and Benign Cold Thyroid Nodules—Preliminary Results
摘要： To evaluate the feasibility and efficacy of single‐fiber laser ablation (LA) under ultrasound guidance and appropriate ablation modes in the treatment of selected metastatic lymph nodes of papillary thyroid carcinoma (PTC) and benign cold thyroid nodules. A total of 18 patients (consisting of 8 patients with 18 metastatic lymph nodes of PTC and 10 patients with 10 benign cold thyroid nodules) each underwent one session of single‐fiber LA under ultrasound guidance. On the basis of the sizes of the nodules, the ablation modes were chosen accordingly. The single‐dot ablation mode was used in the nodules with three orthogonal diameters measuring no greater than 10 mm in diameter, with a dot, a level and an insertion. The double‐dots overlapping ablation mode was used in the nodules with the largest diameters measuring greater than 10 mm (in which the nodules measured no more than 15 mm in diameter and with the other two perpendicular diameters measuring no greater than 10 mm in diameter) with two dots, a level and two insertions. The multiple levels and dots overlapping ablation mode was used in the nodules with the three orthogonal diameters all measuring larger than 10 mm, with multiple dots, levels and insertions. After 12 months of follow‐up in the treated nodules of the metastatic lymph nodes of PTC and benign cold thyroid nodules, the mean baseline volumes decreased from 0.29 ± 0.12 to 0.03 ± 0.03 ml and 3.85 ± 0.64 to 1.1 ± 0.37 ml, respectively, and the mean volume reduction ratios (VRRs), which was calculated as {[(initial volume ?final volume) × 100%]/initial volume}, were 90.3 ± 7.6% and 72 ± 5.8%, respectively. There were six ablative zones that completely disappeared, whereas the ablative zones that still existed presented as scar‐like areas or small hyperechoic areas that were compatible with scar tissue among the 18 malignant nodules at the last follow‐up. Single‐fiber LA under ultrasound guidance, with the appropriate ablation modes, is feasible and effective for the treatment of selected metastatic lymph nodes of PTC and benign cold thyroid nodules. This study suggests that single‐fiber LA may be applied to selected cases with appropriate ablation modes.
关键词： metastatic lymph nodes,ultrasound guidance,papillary thyroid carcinoma,benign cold thyroid nodules,single‐fiber laser ablation
更新于2025-09-19 17:13:59
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Comparative Investigation by Infrared Spectroscopy of the Conformational Metamorphosis of Polyvinylidene Fluoride Under the Action of an Infrared Laser and of γ-Irradiation
摘要： The irradiation of a poly(vinylidene ?uoride) (PVDF) plate with γ-rays up to 100 kGy leads to the breaking of the chain and the formation of unsaturated bonds but practically does not have any e?ect on the conformation composition of PVDF macromolecules. The main conformer, as in native PVDF, is the β form. Irradiation with an IR laser leads to a noticeable carbonization of PVDF macromolecules and is accompanied by a structural transition of polymer macromolecules from the β conformer to the α conformer. In the IR spectrum of the powdered product from laser ablation of PVDF, in addition to the absorption bands of the ablation crater, absorption bands from the parent PVDF are still present.
关键词： poly(vinylidene ?uoride),CO2 laser ablation,IR spectra,γ-irradiation
更新于2025-09-19 17:13:59
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Synthesis and Characterization of Aluminum Nanoparticles Prepared in Vinegar Using a Pulsed Laser Ablation Technique
摘要： The second harmonic wavelength of a neodymium-doped yttrium-aluminum-garnet (Nd-YAG) laser (λ = 532 nm) was used in a pulsed laser ablation technique (PLAL) to synthesize aluminum nanoparticles suspended in white vinegar from an aluminum target. The nanoparticles were characterized by HRTEM and UV-Vis spectrophotometry. They were found to range in size between 2 and 50 nm in diameter, with an average diameter of 12 ± 9 nm. The nanoparticles had a maximum absorption peak at 237 nm and were found to exhibit a core-shell structure with an Al core coated by a thin layer of an amorphous material which could be attributed to amorphous carbon. HRTEM results revealed that the small nanoparticles (<20 nm) had an fcc phase of aluminum crystalline structure, where the larger particles represented alumina (γ-Al2O3) nanoparticles. Such observation suggests that the use of white vinegar as an ablation medium could facilitate the synthesis of aluminum nanoparticles with minimal evidence of the existence of aluminum oxide nanoparticles in the resultant suspension.
关键词： pulsed laser ablation in liquid (PLAL),UV-Vis spectrophotometry,white vinegar,HRTEM,Aluminum nanoparticles
更新于2025-09-19 17:13:59
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Iolite Based Bulk Normalization as 100% (m/m) Quantification Strategy for Reduction of Laser Ablation-Inductively Coupled Plasma-Mass Spectrometry Transient Signal
摘要： Iolite package draw more attention in laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) community in recent years due to its powerful data-handling capacity, excellent signal visualization and open source of calculation codes. In this study, the application of Iolite package was investigated for LA-ICP-MS elemental quantification, and a calculation code for the bulk normalization as 100% (m/m) strategy was compiled. We found that the spline interpolation approach was better than that of linear one for the correction of time-dependent instrument drift. BCR-2G as the quality material was used to assess the proposed code, and the results revealed that the code was practical and reliable. The analytical accuracy was influenced by the used calibration materials. TiO2, MgO, K2O and rare earth elements in BCR-2G were slightly off (5%–10%) when NIST SRM 610 as the calibrator. Cr and Mo were higher (10%–30%) than the recommended values when StHs6/80-G was used as the calibrator. The phenomena would be attributed to the matrix effect or the inaccurate values of corresponding calibrators. Three main sources for the LA-ICP-MS combined uncertainty were recognized, including the uncertainty of recommended values of analytes in calibration material, the uncertainty of measured intensity ratios in sample and the error in bulk normalization as 100% (m/m) strategy. A total of 50 elements in CGSG glass reference materials were quantified based on the proposed Iolite code. Major elements (except MnO, CaO and P2O5) matched well with the recommended values with a discrepancy of 5%, and the trace elements (except Cr, Ni, Zn, Ga, Mo and Sb) were agreement with the recommended values in 10%. The dataset reported in this study was helpful for the value certification of CGSG reference materials. Overall, the proposed Iolite code broadened the application of Iolite package in the reduction of LA-ICP-MS transient signal for the elemental determination.
关键词： CGSG reference material,Combined uncertainty,Laser ablation-inductively coupled plasma-mass spectrometry,Iolite package,Bulk normalization as 100% (m/m)
更新于2025-09-19 17:13:59
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On acoustical registration of irradiated surface displacement during nanosecond laser-metal interaction and metal–nonmetal transition effect
摘要： Laser ablation of mercury is investigated with the help of acoustical monitoring method which uses pulsed modulated laser intensity and piezo-transducer under the irradiated target. Two different trains consisting of 6 and ~70 short peaks (60 ps each) divided with 8 ns intervals are used. The method permits to detect effective displacement of the irradiated surface provided some necessary conditions are fulfilled. The paper purpose is to study influence of possible metal-nonmetal transition on the considered approach. It is found that the observed values of the effective displacement can not be explained in the framework of a simple surface vaporization model. Another interpretation of the results which uses assumption about metal-nonmetal transition is proposed. The assumption is in accordance with our main results: observation of significant acoustic signal shift (70 ns) to earlier times and the signal widening at higher laser fluences (7 J/cm2) for the case of relatively smooth 30 ns laser pulse. Initial part (10 ns) of the shift is observed as well for the train consisting of 6 peaks. The obtained new experimental results can be considered as the first demonstration of metal-nonmetal transition during nanosecond laser ablation.
关键词： metal-nonmetal transition,acoustical monitoring,Laser ablation
更新于2025-09-19 17:13:59
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Fabrication and Deposition of Copper and Copper Oxide Nanoparticles by Laser Ablation in Open Air
摘要： The proximity of the “post-antibiotic era”, where infections and minor injuries could be a cause of death, there are urges to seek an alternative for the cure of infectious diseases. Copper nanoparticles and their huge potential as a bactericidal agent could be a solution. In this work, Cu and Cu oxide nanoparticles were synthesized by laser ablation in open air and in argon atmosphere using 532 and 1064 nm radiation generated by nanosecond and picosecond Nd:YVO4 lasers, respectively, to be directly deposited onto Ti substrates. Size, morphology, composition and the crystalline structure of the produced nanoparticles have been studied by the means of field emission scanning electron microscopy (FESEM), high resolution transmission electron microscopy (HRTEM), the energy dispersive spectroscopy of X-rays (EDS), selected area electron diffraction (SAED) and X-ray diffraction (XRD). The UV-VIS absorbance of the thin layer of nanoparticles was also measured, and the antibacterial capacity of the obtained deposits tested against Staphylococcus aureus. The obtained deposits consisted of porous coatings composed of copper and copper oxide nanoparticles interconnected to form chain-like aggregates. The use of the argon atmosphere contributed to reduce significantly the formation of Cu oxide species. The synthesized and deposited nanoparticles exhibited an inhibitory effect upon S. aureus.
关键词： copper nanoparticles,laser ablation,antibacterial effects
更新于2025-09-19 17:13:59
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Structural and optical properties of nanoparticles formed by laser ablation of porous silicon in liquids: Perspectives in biophotonics
摘要： The paper discusses the possibility of manufacturing silicon nanoparticles, which are suitable for contrasting biological tissues imaged by optical coherence tomography, by femtosecond laser ablation of porous silicon in various liquids. The manufactured nanoparticles are characterised by average sizes of 87, 112, and 102 nm for cases of ablation in water, ethanol, and liquid nitrogen, respectively, as well as a relatively narrow size distribution, which provides additional advantages for subsequent delivery into biological tissues. Electro chemical etching, which results in the formation of layers of porous silicon, allows the yield of ablation products to be increased several-fold by lowering the ablation threshold, thereby increasing the light scattering efficiency of the prepared suspensions compared with the case of using crystalline silicon as targets. The possibility of obtaining high-contrast images of a biotissue phantom based on an agar gel with embedded nanoparticles is shown. The magnitude of the contrast depends on the liquid used for ablation and correlates with the values of the reduced scattering coefficient of the studied suspensions.
关键词： silicon nanoparticles,laser ablation in liquids,atomic force microscopy,light scattering,optical coherence tomography,spectrophotometry
更新于2025-09-19 17:13:59
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Zn1 a?? xCdxS Nanoparticles Obtained by Laser Ablation
摘要： Approximately spherical nanoparticles of the II–VI semiconductor materials Zn1 – xCdxS have been produced successfully by laser ablation of the bulk material in several liquids. The non-stabilized suspensions of particles are characterized by absorption spectroscopy and transmission electron microscopy (TEM). The procedure is not strongly size-selective, radii of 7 ± 3 nm were found for Zn1 – xCdxS by transmission electron microscopy. Acetonitrile stabilizes the particles for several days up to weeks. Prolonged irradiation leads effectively to a reduction in particles size, in which particle agglomeration may play an important role. Ablation in degassed liquids does not have a significant effect on the absorption of the suspended particles.
关键词： Zn1 – xCdxS nanoparticles,laser ablation,absorption spectroscopy,transmission electron microscopy,quantum confinement
更新于2025-09-19 17:13:59