Species stratification and local plasma composition can affect microsecond-timescale oxidation reaction rates of metals such as Al in an oxidizing atmosphere. Here, we utilize fast, gated emission ...spectroscopy and a high-speed framing camera to determine the intensity and spatiotemporal evolution of various Al ablation products within a laser-induced plasma. Using a high-purity Al plate, micron- and nano-sized Al powders, and inert micron Al
2
O
3
powder, we studied the effect of Al morphology and reactivity on the oxidation characteristics and plasma hydrodynamics in air at 1 atm over two temporal regimes (2–10 μs and 20–100 μs). We observed an increase in the spatial distribution and intensity of emission from vaporized Al within the plasma for powder-based samples compared to plate Al due to enhanced material dispersion. In nano-Al, AlO emission forms at, and propagates along, the surface of the powder bed from 2–10 μs, whereas for micron powder, there is a delay in AlO formation within the bulk of the plasma until tens of microseconds. We measured electron densities from a variety of spectral lines, which can range from ~ 2 × 10
15
to 2 × 10
18
cm
−3
, and which scale inversely with the rate of plasma expansion across morphologies. The Al I and Al II species temperatures from 2 to 10 μs calculated via Boltzmann plots are similar (from ~ 10,000 to 14,000 K), and we performed a suite of local thermodynamic equilibrium (LTE) validity calculations to establish that these two species are in LTE, while H is not. Using image co-registration, we calculated the thickness of the AlO layer surrounding the expanding Al cloud at times > 20 μs, which can range from ~ 50 to 300 μm. These results allow us to begin to understand the complexities of laser ablated metal powder reactions at microsecond timescales.
A novel “wave” signal-smoothing and mercury-removing device has been developed for laser ablation quadrupole and multiple collector ICPMS analysis. With the wave stabilizer that has been developed, ...the signal stability was improved by a factor of 6.6–10 and no oscillation of the signal intensity was observed at a repetition rate of 1 Hz. Another advantage of the wave stabilizer is that the signal decay time is similar to that without the signal-smoothing device (increased by only 1–2 s for a signal decay of approximately 4 orders of magnitude). Most of the normalized elemental signals (relative to those without the stabilizer) lie within the range of 0.95–1.0 with the wave stabilizer. Thus, the wave stabilizer device does not significantly affect the aerosol transport efficiency. These findings indicate that this device is well-suited for routine optimization of ICPMS, as well as low repetition rate laser ablation analysis, which provides smaller elemental fractionation and better spatial resolution. With the wave signal-smoothing and mercury-removing device, the mercury gas background is reduced by 1 order of magnitude. More importantly, the 202Hg signal intensity produced in the sulfide standard MASS-1 by laser ablation is reduced from 256 to 0.7 mV by the use of the wave signal-smoothing and mercury-removing device. This result suggests that the mercury is almost completely removed from the sample aerosol particles produced by laser ablation with the operation of the wave mercury-removing device. The wave mercury-removing device that we have designed is very important for Pb isotope ratio and accessory mineral U–Pb dating analysis, where removal of the mercury from the background gas and sample aerosol particles is highly desired. The wave signal-smoothing and mercury-removing device was applied successfully to the determination of the 206Pb/204Pb isotope ratio in samples with low Pb content and/or high Hg content.
There is an abundance of published trace element data for sphalerite, galena and chalcopyrite in natural systems, yet for a co-crystallized assemblage comprising these base metal sulphides, there is ...no detailed understanding of the preferred host of many trace elements. Laser-ablation inductively-coupled plasma mass spectrometry trace element maps and spot analyses were generated on 17 assemblages containing co-crystallized sphalerite and/or galena and/or chalcopyrite from 9 different ore deposits. These deposits are representative of different ore types, geologic environments and physiochemical conditions of ore formation, as well as superimposed syn-metamorphic remobilisation and recrystallization. The primary factors that control the preferred base metal sulphide host of Mn, Fe, Co, Cu, Zn, Ga, As, Se, Ag, Cd, In, Sb, Te, Tl and Bi are element oxidation state, ionic radius of the substituting element, element availability and the maximum trace element budget that a given sulphide mineral can accommodate. Temperature, pressure, redox conditions at time of crystallization and metal source, do not generally appear to influence the preferred base metal sulphide host of all the trace elements. Exceptions are Ga, In and Sn recrystallized at high metamorphic grades, when the preferred host of Ga and Sn usually becomes chalcopyrite. In more typical lower temperature ores, the preferred host of Ga is sphalerite. Indium concentrations also increase in chalcopyrite during recrystallization. At lower temperatures the partitioning behaviour of Sn remains poorly constrained and shows little predictable pattern among the data here. The results obtained may be used as a tool to assess co-crystallization. If trace element distributions in a given base metal sulphide assemblage match those reported here, and assuming those distributions have not been significantly altered post (re-) crystallization, then it may be suggestive of a co-crystallized assemblage. Such information provides a foundation for novel attempts to develop trace element-in-sulphide geothermometers.
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•Trace element partitioning between co-crystallized sulphides is predictable.•Partitioning primarily depends on factors intrinsic to the elements and sulphides.•Partitioning depends little on external factors such as temperature and pressure.•Only high metamorphic conditions affect the partitioning of some elements.
Summary
Analysis of wood transects in a manner that preserves the spatial distribution of the metabolites present is highly desirable to among other things: (1) facilitate ecophysiology studies that ...reveal the association between chemical make‐up and environmental factors or climatic events over time; and (2) investigate the mechanisms of the synthesis and trafficking of small molecules within specialised tissues. While a variety of techniques could be applied to achieve these goals, most remain challenging and impractical.
Laser ablation direct analysis in real time imaging–mass spectrometry (LADI‐MS) was successfully used to survey the chemical profile of wood, while also preserving the small‐molecule spatial distributions. The tree species Entandrophragma candollei Harms, Millettia laurentii DeWild., Pericopsis elata (Harms) Meeuwen, Dalbergia nigra (Vell.) Benth. and Dalbergia normandii Bosser & R.Rabev were analysed.
Several compounds were associated with anatomical features. A greater diversity was detected in the vessels and parenchyma compared with the fibres. Analysis of single vessels revealed that the chemical fingerprint used for timber identification is mainly determined by vessel content.
Laser ablation direct analysis in real time imaging–mass spectrometry offers unprecedented opportunities to investigate the distribution of metabolites within wood samples, while circumventing the issues associated with previous methods. This technique opens up new vistas for the discovery of small‐molecule biomarkers that are linked to environmental events.
Femtosecond laser surface processing is a technology that can be used to functionalize many surfaces, imparting specialized properties such as increased broadband optical absorption or ...superhydrophilicity/superhydrophobicity. In this study, two unique classes of surface structures, below surface growth (BSG) and above surface growth (ASG) mounds, were formed by femtosecond laser surface processing on amorphous and polycrystalline Ni
Nb
with two different grain sizes. Cross sectional imaging of these mounds revealed thermal evidence of the unique formation processes for each class of surface structure. BSG mounds formed on all three substrates using the same laser parameters had similar surface morphology. The microstructures in the mounds were unaltered compared with the substrate before laser processing, suggesting their formation was dominated by preferential valley ablation. ASG mounds had similar morphology when formed on the polycrystalline Ni
Nb
substrates with 100 nm and 2 H9262m grain size. However, the ASG mounds had significantly wider diameter and higher peak-to-valley heights when the substrate was amorphous Ni
Nb
. Hydrodynamic melting was primarily responsible for ASG mound formation. On amorphous Ni
Nb
substrates, the ASG mounds are most likely larger due to lower thermal diffusivity. There was clear difference in growth mechanism of femtosecond laser processed BSG and ASG mounds, and grain size does not appear to be a factor.
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•Charging effect on NPs produced with ns-PLAL.•Computation of NPs cloud electrostatic pressure after PLAL.•NPs releasing because of electrostatic pressure exceeds the Bubble ...pressure.•Dynamic of NPs releasing in solution during PLAL.
The laser induced plasma during the nanosecond Pulsed Laser Ablation in Liquid (PLAL) plays a crucial role in the nanoparticles (NPs) formation and charging. It was demonstrated that during the plasma phase evolution, once the NPs are formed, they are charged with the excess of plasma electrons. Immediately after the plasma phase extinguishes, the NPs will be released in the induced vapor bubble, generated by the fast energy exchanges between the plasma and the liquid. The excess of charge in the NPs preserves them from the agglomeration during the bubble evolution and can induces an electrostatic pressure able to eject the particles outside the cavitation bubble.
In this work, the plasma charging effect on the particle releasing in solution, during the bubble evolution, has been investigated. Temporal evolution of laser induced bubble on silver target immersed in water has been measured with the shadowgraph technique. Then, starting from the experimental bubble radius evolution, the releasing of the NPs from the cavitation bubble to the liquid has been modeled by comparing the electrostatic pressure of the charged NPs cloud and the pressure of the cavitation bubble. The following discussion proposes a new insight of the mechanism of NPs releasing in solution.
The chronologic record encoded in accessory minerals, based on the radioactive decay of U and Th, is indispensable to extract quantitative process rates over timescales encompassing Earth's evolution ...from the Hadean to the Holocene, and extending from terrestrial to extra-terrestrial realms. We have essentially three different U–Pb dating tools at hand, a high-precision, whole-grain bulk technique (isotope-dilution thermal ionization mass spectrometry, ID-TIMS), and two high-spatial resolution but less precise in-situ techniques (secondary ion mass spectrometry, SIMS, and laser ablation inductively-coupled plasma mass spectrometry, LA-ICP-MS), all of which are predominantly applied to the mineral zircon. All three have reached a technological and methodological maturity in data quality and quantity, but interpretational differences, which are often common (albeit at different temporal and spatial scales) to all isotopic dating techniques, remain largely unresolved. The choice to use one of these techniques should be governed by the scientific question posed, such as (1) the duration of the geological process to be resolved; (2) the size and abundance of the material to be analyzed; (3) the complexity of the sample material and of the geological history to be resolved; and (4) the number of dates needed to address the question. Our compilation demonstrates that, ultimately, the highest confidence geochronological data will not only result from the optimal choice of appropriate analysis technique and the accurate treatment of analytical and interpretational complexities, but also require comprehensive sample characterization that employs the full gamut of textural (e.g., cathodoluminescence, charge contrast imaging, electron backscatter diffraction) and compositional (e.g., trace element, stable and radiogenic isotope) analysis.
The physiochemical properties of Polyvinyl Alcohol (PVA) film was enhanced by embedding with nanostructured metal oxides (CdO, Al2O3, and Cu2O) via one-pot and green method, nanosecond Nd:YAG pulsed ...laser ablation in liquids technique (PLAL). This process was carried by ablation of metal targets (cadmium, copper, and aluminum) immersed in PVA solution by high intensity pulsed laser in the focusing condition. The enhancing of the PVA properties were appeared by studying the structure, optical and morphology of the prepared films before and after embedding by several technique as X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), UV–Visible, Photoluminescence (PL), Scanning electron microscope (SEM) and energy dispersive X-ray spectroscopy (EDX). From structural investigation, the XRD patterns showed a reduction of CdO, Al2O3, and Cu2O nanoparticles within PVA chain. From optical investigation, the interaction and the structural modifications occurred between PVA chains and each metal oxide nanoparticles appeared in stretching vibration bands, the optical energy band gap (Eg) values by using Tauc equation equaled to 2.33, 3.63, and 3.54 eV for the oxide of Cd, Al, and Cu, respectively, are a good agreement with previous work, and the Photoluminescence spectra showed decreasing in emission intensity in the case of embedding with metal oxides. From morphological investigation, the FE-SEM images showed a homogeneous distribution with spherical shape of metal oxides through the polymer of PVA. The qualitative and semi-quantitative elemental analysis of the prepared samples via EDX technique confirmed the embedding of the metal oxide in the PVA structure. This work helps to open the route to produce various properties of PVA by embedded with different nanostructured metal oxides.
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•Metal oxide nanoparticles are synthesized by laser ablation in liquid media technique.•PVA doped with metal oxide nanoparticles have been synthesized via single step.•The doping process was carried inside the liquid media.•PVA/metal oxides composite structure has high purity form without any by-product.•The structural, compositional and optical properties of the prepared samples were studied.
In this study, Polyvinyl Pyrrolidone (PVP)/Polyvinyl Alcohol (PVA) blend embedded by gold nanoparticles (AuNPs) was synthesized via traditional casting method to study the enhanced electrical ...conductivity of the blend. AuNPs were synthesized by Laser Ablation in Liquids Technique (PLAL). The physical characterization of the prepared PVP/PVA/AuNPs films have been performed by various techniques. The electrical conductivity of the prepared samples was evaluated. The structural characterization shows significant sharp diffraction peak at 2 theta = 38° attributed to the plane (111) related to the presence of AuNPs. UV–Vis absorption spectra reveals the distinctive peak of AuNPs at 536 nm. SEM diffractograms approve the embedding of AuNPs in the surface of PVP/PVA. The electrical conductivity data approved enhancement the performance of the pure blend PVP/PVA after embedded with AuNPs prepared by laser ablation. Ac conductivity have been increased by increasing the ratio of AuNPs within PVP/PVA blend. Thus, these observations reflect the use of PVP/PVA/AuNPs samples in electrical applications.
•Gold nanoparticles have been prepared via laser ablation process.•PVP/PVA/AuNPs films were well prepared by casting technique.•XRD approved proved the embedding of AuNPs in PVP/PVA matrix.•UV–visible showed the appearing of SPR absorption peak of the embedded AuNPs.•The values of σac' are increased as AuNPs increased in PVP/PVA at higher frequencies.
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•Multiscale design of 3D MOF (M−BTC, M: Cu, Co, Ni) was demonstrated via PLAL.•Studied intrinsic properties on electrocatalytic active-states for overall water splitting.•Co-BTC ...achieve low η10 of 437 and 370 mV for HER and OER, respectively.•Require only 2.03 V @ 10 mA/cm2 for Co–BTC ∥ Co–BTC full electrolysis system.•Electronic effect implying on structural stability and long-term durability.
Multiscale structural engineering of high-performance bifunctional electrocatalysts to influence hydrogen and oxygen evolution reactions (HER and OER) has a significant role in overall water splitting. Thus, we successfully designed a new strategy and synthesized transition-metal-based 3D metal–organic framework (MOF) materials having various architectures, namely, Cu–BTC, Co–BTC, and Ni–BTC, by pulsed laser ablation in dimethylformamide. The coordination between the metal and carboxylate moieties of the ligand, crystalline structure, phase purity, morphology, thermal stability, and oxidation states were illustrated using physical characterization techniques. Further, intrinsic properties of the MOF materials were studied using electrocatalytic reactions toward HER and OER in an alkaline medium. Among the synthesized MOF materials, the Co–BTC electrocatalyst showed a very low overpotential of 437 mV toward HER at a constant current density of 10 mA cm−2 in 1.0 M potassium hydroxide. The derived Tafel slope and Rct values are 115.1 mV dec−1 and 2.77 Ω cm−2, respectively. Similarly, OER studies reveal that the Co–BTC MOF showed robust activity with low overpotential of 370 mV at 10 mA cm−2. Finally, the optimal Co–BTC MOF electrode required 2.03 V of cell potential to deliver 10 mA cm−2 in a dielectrode (Co–BTC ∥ Co–BTC) electrolysis system with long-run stability. The present report reveals a new possibility for the innovation in robust HER and OER bifunctional electrocatalysts using nonprecious metallic MOF materials.
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