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Quantitative in situ mapping of elements in deep-sea hydrothermal vents using laser-induced breakdown spectroscopy and multivariate analysis
摘要： This study describes a method to quantify the chemical composition of deep-sea hydrothermal deposits in situ using laser-induced breakdown spectroscopy (LIBS). Partial least squares (PLS) regression analysis is applied to spectra obtained using a long laser pulse with a duration of 150 ns. The number of measurements needed to address the spatial heterogeneity of samples is determined through high-resolution mapping of the elemental distribution in rock samples. PLS applied to laboratory measured seawater-submerged samples achieved an average relative error (RE) of 25% for Cu, Pb, and Zn compared to benchmark concentration values in cross-validation and validation studies, where both the benchmark concentration values and LIBS spectral data are made available with this publication. The PLS model was applied to LIBS signals obtained in situ from hydrothermal deposits at 1000 m depth in the ocean. The results show that target inhomogeneity limits the accuracy of the surface LIBS measurements compared to benchmark values from bulk analysis of samples. Making multiple measurements with small position offsets at each location improves the accuracy of estimates compared to an equivalent number of measurements at a single position. Maps of element distribution generated using quantified in situ data demonstrate how chemical survey outputs can be generated by combining LIBS with multivariate analysis. This enables real-time chemical feedback during deep-sea operations and chemical surveys in situations or with platforms where sample recovery is not possible.
关键词： Multivariate analysis,Laser-induced breakdown spectroscopy (LIBS),Deep-sea explorations,In situ chemical analysis,Seafloor mineral resources,Partial least squares regression analysis
更新于2025-09-23 15:19:57
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Au@Ag nanorod horizontal arrays: Self-assembly preparation and in situ monitoring SERS of plasmonic catalytic reaction
摘要： Here, we successfully synthesized silver-coated gold nanorods (Au@Ag NRs) via a facile wet chemical method. The catalytic property of Au@Ag NRs in water solution was much better than that of Au NRs in water solution. To obtain high catalytic properties, we self-assembled a single-layer Au@Ag NR array by evaporation on a silicon wafer. The catalytic activity of the Au@Ag NR array was probed using the reduction of 4-nitrothiophenol. The reaction processes were monitored and identified through in situ surface-enhanced Raman spectroscopy based on the confocal Raman microscope system. This study provides a simple and fast method to improve the catalytic property of the noble nanoparticles.
关键词： In situ monitoring,Self-assembly,Au@Ag nanorods,Plasmonic catalytic reaction,SERS
更新于2025-09-23 15:19:57
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An investigation on the measurement of instantaneous temperatures in laser assisted additive manufacturing by thermal imagers
摘要： Powder bed fusion additive manufacturing processes has started to be investigated by means of temperature distribution and change on parts, since problems such as residual stresses, deformations, microstructural differences and lack of mechanical properties were observed due to temperatures of parts during manufacturing. In the current studies, thermal cameras were used to analyze thermal history of parts. Depending on the accuracy of thermal cameras, temperature values were varied. In this study, a mathematical model which was supported by the data of experimental tests was developed to obtain increased accuracy. Melt pool temperatures were predicted by using the model which consisted of average temperature and extrapolated measurement area approaches. Melt pool temperatures were calculated ranging between 1700 and 2800 °C. Besides, temperature-dependent cooling rate was considered in the model to improve accuracy of temperature measurement. In addition, finite element analysis of manufacturing process was performed to verify results. Comparison between results of the mathematical equations and finite element analysis showed the accuracy as minimum 85% and maximum 98%. A trusted equation was generated to calculate melt pool temperatures by using an ordinary thermal imager.
关键词： Thermal imager,Additive manufacturing,Powder bed fusion,In-situ monitoring
更新于2025-09-23 15:19:57
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Resistive-type UVa??visible photodetector based on CdS NWs /ZnO nanowalls heterostructure fabricated using in-situ synthesis method
摘要： Here, the resistivity-type UV-visible photodetectors are designed and fabricated by implementation of direct integration between CdS nanowires(NWs) and vertical standing ZnO nanowalls with a facile in-situ synthesis method, in which ZnO nanowalls are employed as good support for anchoring well-dispersed CdS NWs to overcome its random distribution. The photodetectors based on CdS/ZnO heterojunctions demonstrate higher photo response activity than the prinstine CdS NWs and pure ZnO nanowalls photodetectors . The high performance could be attributed to the charge carrier separation efficiency and fast charge transportation facilitated by effective and close contact between CdS NWs and ZnO nanowalls. The results indicate that the ZnO/CdS heterojunctions fabricated by in-situ synthesis method provide a facile approach for nanoscale optoelectronic device.
关键词： photodetector,in-situ synthesis,CdS NWs,ZnO nanowalls
更新于2025-09-23 15:19:57
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Interfacial engineering and film-forming mechanism of perovskite films revealed by synchrotron-based GIXRD at SSRF for high-performance solar cells
摘要： Organic-inorganic hybrid perovskites as promising light-harvesting materials have been the focus of scientific research and development of photovoltaics recently. Especially, metal halide perovskites currently become one of the most competitive candidates for the fabrication of solar cells with record certified efficiency over 25%. Despite the high efficiency, many fundamental questions remain unclear and need to be addressed at both the material and device levels, such as weaker stability, poorer reproducibility, easier degradation influenced by water, oxygen, thermal factors, and so on. Based on recent reports, interfacial engineering plays a crucial role in controlling the behavior of the charge carriers and in growing high quality, defect-free perovskite crystals, therefore helping to enhance device performance and operational stability. However, little attention has been paid to the interface interaction mechanism among carrier transport layers and perovskite active layer. It is extremely urgent to explore the perovskite interfaces in details and to find out how its interface structure is relative to the efficiency and hysteresis in perovskites solar cells. Based on the Shanghai Synchrotron Radiation Facility (SSRF), we have established an advanced perovskite photovoltaic device preparation and in-line test system, developed a series of unique surface diffraction analysis methods based on ex situ and in situ grazing incidence X-ray diffraction (GIXRD), and reported a large number of novel synchrotron radiation results on crystallization of the perovskite photovoltaics films. Our main investigations are aimed to deeply in-situ study the perovskite film growth dynamics using synchrotron radiation GIXRD technology in combination with a customized mini online glove box (c(H2O,O2)<1 ppm) and temperature-humidity control equipment, and so on., which should provide solid theoretical background and point to the useful direction for designing and fabricating high-performance perovskites solar cells. Moreover, a multi-functional joint characterization technology that in-situ GIXRD simultaneously combines with conventional characterization methods at synchrotron radiation beamline station must be put on the agenda in future research, which greatly promotes much more comprehensive and intuitive understanding of the nucleation, microcrystallization, and degradation mechanisms of perovskite heterojunction films, and therefore further optimizing their chemical synthesis strategies at the molecular level for functional materials.
关键词： Growth dynamics,Perovskites solar cells,Device performance,Grazing incidence X-ray diffraction,In-situ study
更新于2025-09-23 15:19:57
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In situ chemical composition analysis of a tungsten-inert-gas austenitic stainless steel weld measured by laser-induced breakdown spectroscopy
摘要： The chemical composition of a weld metal determines the resulting solidification mode of stainless steel and the consequent weld metal quality. In this work tungsten inert gas (TIG) welding of EN grade 1.4435 austenitic stainless steel was monitored using laser-induced breakdown spectroscopy (LIBS) for the in situ measurement of chemical composition changes. This research aims to prototype a real-time chemical composition analysis system for welding applications and prove the feasibility of such quality control loop. LIBS was used to investigate in situ the monitoring of metal vaporization during TIG welding. We found Mn vapor formation above the weld pool and subsequent condensation of Mn on the weld metal surface using LIBS. Post-weld line scans were conducted by LIBS on various welds produced with different welding currents. Local changes of Ni and Mn were observed at higher welding currents. The results are in good agreement with the literature and proved that LIBS can be used in situ to inspect the TIG welding process.
关键词： LIBS,In situ measurement,Metal vapor,Welding,Austenitic stainless steel
更新于2025-09-23 15:19:57
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Kinetic and Mechanistic Investigation of the Photocatalyzed Surface Reduction of 4-Nitrothiophenol Observed on a Silver Plasmonic Film via Surface-Enhanced Raman Scattering
摘要： Hot electrons generated by photo-induced plasmon decay from plasmonic metal surface can reduce 4-nitrothiophenol (4-NTP) to 4-aminothiophenol (4-ATP). Comparing to the reduction with a reducing agent such as sodium borohydride, Surface-Enhanced Raman scattering (SERS) measurements were performed here to elucidate the complex molecular mechanism of the reduction in presence of halide ions and hydrogen ions. The SERS measurements were performed using a simply prepared silver plasmonic film (AgPF), which enables monitoring of the reaction in different conditions at a solid-liquid surface, and eliminates the need for use of a reducing agent. As the concentration of H+ and Cl- could controlled, the observation of the reaction under a systematic set of condition was possible. Based on the kinetic traces of the intermediates, a reaction mechanism for the 4-NTP to 4-ATP reduction is suggested. Rate constants for the individual reactions are presented that fit the measured kinetic traces, and the role of hydrogen in each reaction step is characterized. This work provides clarification on the molecular transformation directly using protons as hydrogen source and demonstrates an effective method of applying a simple and low-cost silver surface catalyst for SERS studies. Moreover, the monitoring of Cl--concentration-dependent spectra gained insight into the hot-electron conversion process during the photoreduction and strongly support the formation of AgCl for activation of H+.
关键词： in-situ SERS spectra,kinetic rate constants,reaction mechanism,time-resolved measurements,selective surface photocatalytic reaction
更新于2025-09-23 15:19:57
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In situ reactions during direct laser deposition of Ti-B4C composites
摘要： Direct laser deposition of a mixture of titanium (Ti) and boron-carbide (B4C), using the laser engineered net shaping process, results in a complex multi-phase Ti matrix composite due to the incipient interfacial reactions between liquid titanium and solid/partially melted B4C. Detailed microstructural characterization, at multiple length scales, reveals that titanium boride (TiB) precipitates are the initial reaction product which act as heterogeneous nucleation sites for TiC precipitates. Both the TiB and TiC precipitates in turn act as heterogeneous nucleation sites for fine β-Ti grains, within the retained liquid titanium, which eventually transform into fine equiaxed α-Ti grains comprising the matrix.
关键词： Titanium matrix composites,In-situ reactions,Boron,Additive manufacturing,Carbide
更新于2025-09-23 15:19:57
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Estimation of Forest Growing Stock Volume with UAV Laser Scanning Data: Can It Be Done without Field Data?
摘要： Laser scanning data from unmanned aerial vehicles (UAV-LS) offer new opportunities to estimate forest growing stock volume (V) exclusively based on the UAV-LS data. We propose a method to measure tree attributes and using these measurements to estimate V without the use of field data for calibration. The method consists of five steps: i) Using UAV-LS data, tree crowns are automatically identified and segmented wall-to-wall. ii) From all detected tree crowns, a sample is taken where diameter at breast height (DBH) can be recorded reliably as determined by visual assessment in the UAV-LS data. iii) Another sample of crowns is taken where tree species were identifiable from UAV image data. iv) DBH and tree species models are fit using the samples and applied to all detected tree crowns. v) Single tree volumes are predicted with existing allometric models using predicted species and DBH, and height directly obtained from UAV-LS. The method was applied to a Riegl-VUX data set with an average density of 1130 points m?2 and 3 cm orthomosaic acquired over an 8.8 ha managed boreal forest. The volumes of the identified trees were aggregated to estimate plot-, stand-, and forest-level volumes which were validated using 58 independently measured field plots. The root-mean-square deviance (RMSD%) decreased when increasing the spatial scale from the plot (32.2%) to stand (27.1%) and forest level (3.5%). The accuracy of the UAV-LS estimates varied given forest structure and was highest in open pine stands and lowest in dense birch or spruce stands. On the forest level, the estimates based on UAV-LS data were well within the 95% confidence interval of the intense field survey estimate, and both estimates had a similar precision. While the results are encouraging for further use of UAV-LS in the context of fully airborne forest inventories, future studies should confirm our findings in a variety of forest types and conditions.
关键词： in-situ data,Riegl-VUX,UAV-LS,drone,forest inventory
更新于2025-09-23 15:19:57
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Barium doping effect on the photovoltaic performance and stability of MA0.4FA0.6BaxPb1-xIyCl3-y perovskite solar cells
摘要： Perovskite solar cells (PSCs) have earned widespread attention owing to its fast-growing power conversion efficiency (PCE). However, there are some challenges for this type of solar cells. The toxicity issue, current density-voltage (J-V) hysteresis, and uncertain stability hinder commercialization. In this study, we developed the PSCs with MA0.4FA0.6BaxPb1-xIyCl3-y film as active layer. The MA0.4FA0.6BaxPb1-xIyCl3-y film with various barium doping concentrations were fabricated by solvent engineering method. We investigate the surface morphology, crystal orientation, and optical property of various perovskite films. Furthermore, the in situ grazing-incidence wide-angle X-ray scattering (in-situ GIWAXS) is used to analyze the heating crystallization process of perovskite film. We discover that Ba can improve crystallinity and structural stability. For the optimal 5.0 mol% Ba replacement, the PCE of perovskite device is increased to 17.4%, the J-V hysteresis can be completely eliminated and the device demonstrates long-term stability.
关键词： in-situ GIWAXS,perovskite solar cell,J-V hysteresis,barium dopant,power conversion efficiency
更新于2025-09-23 15:19:57