Aqueous Solutions Of Metal Salts Research Articles

Sorption-desorption of rare earth metal cations by ferromanganese crusts of Govorov’s guyote of the Magellanic Mountains of the Pacific Ocean

The article presents the results of experimental studies on the sorption and desorption of rare earth metal (REM) cations by cobalt-rich ferromanganese crusts (CMC) of Govorov’s guyot. It has been established that the sorption of REM cations occurs on the ore minerals KMK – Fe-vernadite, vernadite, Mn-feroxygite, goethite. The crusts are characterized by a high exchange capacity – 1.78–3.57 mg-eq/g, which increases in a series: (Dy Gd Lu Sm Nd Y, La Eu) Ce. The sorption of REM cations proceeds by an ion exchange equivalent irreversible mechanism. The exchange complex of ore minerals consists of Na+, K+, Ca2+, Mg2+ cations, which contribute 97‒98% to their total capacity. The crusts are characterized by the group sorption of REM cations from multicomponent aqueous solutions of metal salts. The selectivity of ore manganese and ferruginous minerals of crusts to REM cations is significantly higher than to the main cations of ocean water. From experimental data on the desorption of sorbed REM cations with NaCl solution, their irreversible absorption by ore minerals follows, and the strengthening of the chemical bond of sorbed REM cations with the main structural elements of these minerals over time. An important property of ore minerals, primarily manganese minerals, is their chemical and structural stability in aqueous solutions of electrolytes. This suggests the repeated use of ferromanganese crusts as sorbents of REM cations.

Effect of Halide Ion Additives during Electrodeposition of Nanocatalysts

Platinum (Pt) and platinum ruthenium (PtRu) alloy catalysts are of interest for the development of green energy technologies such as hydrogen and direct methanol fuel cells. However, the high cost of Pt dictates that the precious metal be used as efficiently as possible so the surface area available to catalyze reactions per mass is maximized. Alloying Pt with different metals such as Ru is also of interest due to the increased activity and tolerance to contaminants that the additional metal imparts to the Pt. Industrial nanoparticle synthesis depends on scalable techniques such as electrodeposition. And a feature of this technique is that the morphology of electrodeposited structures is heavily influenced by the composition of the electrodeposition solution.This work describes how the presence of excess Cl- and Br- ions in an aqueous solution of metal salts affects the morphology of Pt and PtRu electrodeposited onto glassy carbon electrode substrates. The addition Br- ions and mixtures of the two halides resulted in smaller nanoparticles as observed by scanning electron microscopy and, therefore, higher surface areas compared to Pt electrodeposited in the absence of these halide species. Consequently, the mass activity towards the oxygen reduction reaction, one half of the reaction in hydrogen fuel cells, was highest when Pt was electrodeposited in the presence of Br- ions. The PtRu particles were also tested for their activity and resistance to carbon monoxide poisoning as a function of composition and halide additives. These results show that halide ions can be used beneficially in electrocatalyst synthesis without a negative impact on the activity of these catalysts, in contrast to what has been suggested in some prior studies. Presented herein is a simple method to tune the surface area and properties of electrodeposited nanocatalysts.1 Gautam, S.; Hadley, A. M. K.; Gates, B. D. Controlled Growth of Platinum Nanoparticles during Electrodeposition using Halide Ion Containing Additives. J. Electrochem. Soc. 2022, 169, 112508.

Investigation of the Complexation Activity of 2,4-Dithiouracil with Au(III) and Cu(II) and Biological Activity of the Newly Formed Complexes

The goal of this study is to synthesize, determine the structure, and examine the antimicrobial properties of novel Cu(II) and Au(III) complexes of 2,4-dithiouracil and its derivatives. These complexes were obtained by mixing aqueous solutions of the corresponding metal salts with the ligand dissolved in DMSO and aqueous NaOH, using a metal-to-ligand ratio of 1:4:2. The structures of the new compounds were analyzed by melting point determination, microwave plasma atomic emission spectrometry (MP-AES) for Cu and Au, inductively coupled plasma optical emission spectrometry (ICP-OES) for S, attenuated total reflection (ATR), solution and solid-state NMR, and Raman spectroscopy. The data for 2,4-dithiouracil obtained from the 1H NMR, 13C NMR, distortionless enhancement by polarization transfer spectrum (DEPT-135), proton–proton homonuclear correlation spectrum (1H-1H COSY), long-range 1H-13C heteronuclear multiple bond correlation experiment (HMBC), and heteronuclear single quantum coherence spectra (HSQC) aided the interpretation of the NMR data for the gold and copper complexes. Furthermore, the antimicrobial effect of the free ligands and their complexes was assessed against Gram-positive and Gram-negative bacteria, as well as yeasts.

Transition metal salt catalysed green synthesis of mesoporous silica nanoparticles

Conventionally, mesoporous silica nanoparticles are prepared by catalysing silicon alkoxides using acids or bases and are highly important in storage, delivery, and catalysis. Here, for the first time, we demonstrate that a transition metal ion (such as Ni(II), Co(II), and Mn(II)) also catalyses the hydrolysis and condensation reactions of silicon alkoxides in aqueous media without any additional acid or base to synthesize mesostructured and micro/mesostructured silica nanoparticles. An aqueous solution of a transition metal salt (specifically, nitrate salts of Ni(II), Co(II), or Mn(II), or chloride and sulphate salts of Ni(II)), 10-Lauryl ether (C12H25(OCH2CH2)10OH, C12E10) and cetyltrimethylammonium bromide (C16H33N(CH3)3Br, CTAB), and tetramethyl orthosilicate (TMOS) undergoes a precipitation reaction at room temperature, yielding ultra-small ordered mesostructured silica nanoparticles. These nanoparticles are subsequently calcined to produce mesoporous silica (meso-SiO2) with a high surface area (680–871 m2/g), large pore-volume (2.2–3.71 cm3/g), and small pore-size (1.2–3.0 nm). Moreover, the counter anions of the salts play an important role in the assembly process to obtain nanoparticles with an additional well-defined secondary pore (7.5–33.4 nm or larger). Coordinated water of the metal ion and methoxy group of the silica source react to produce a complex in which two hydroxy sides are in close vicinity to speed up the condensation reaction. We propose a hydrolysis and condensation reaction mechanism for TMOS to highlight the role of the metal ion as a catalyst.

Metal Painting by Plasma Jet

AbstractConducting metal interconnections are essential to link electronic components or multiple circuits for electronic device fabrication. Scalable, rapid, and sustainable methods for printing adherent metal interconnections on dielectric materials are lacking, which stifles the development of new electronic consumer devices. Here a breakthrough single‐step and rapid process to deposit highly conducting metal tracks is introduced, using an atmospheric pressure plasma jet. The deposition process used a rudimentary aqueous solution of metal salts as ink, that was introduced as a mist into a helium plasma gas. The metal salt was reduced and deposited with spatiotemporal control using a plasma jet generated at radio frequency with 15 W power at room temperature and pressure. The conductive metal layers were highly adhesive on glass, ceramics, polymeric materials, even biological surfaces such as plant leaves and animal skin, depostedwith little damage to the substrate. The conductivity of deposited tracks on glass shows 50.8 ± 8.6% and 5.2 ± 1.6% of bulk silver and copper metal conductivity respectively.

Synthesis and characterization of novel quinaldic acid based Ni, Fe, and Cr Complexes: A computational and experimental study

Complexes ([Ni(quin-2-c)2(H2O)2]•2H2O, [Fe(quin-2-c)2(H2O)2], [Cr(quin-2-c)2(H2O)2] were synthesized from aqueous solutions of metal salts, quinaldic acid, and semicarbazide. In the crystal structure of the first complex, the nickel atom is chelated by the deprotonated quinaldic acid molecule through the oxygen atom of the carboxyl group, and the heterocyclic nitrogen atom, as well as two water molecules, are coordinated. The other two water molecules are located in the outer sphere. In the structure of the iron and chromium complexes, the metal atoms have a similar complex formation but do not have water molecules in the outer sphere. In all compounds, quinaldic acid acts as a bidentate ligand to form five-membered metallocycles. The electronic structure properties were investigated through theoretical modeling using the B3LYP method at the 6–31 + G(d,p) computational level. Density functional theory (DFT) was employed in quantum chemistry simulations to refine proposed structures and explore the characteristics of frontier orbitals via analysis of frontier molecular orbitals (FMOs). These computations facilitated the identification of specific sites on the surface of molecules by generating molecular electrostatic potential maps and provided insights into the structural and reactive properties. Hirshfeld surface analysis was conducted to examine intermolecular interactions, revealing a prevalence of H⋅⋅⋅H interactions.

Synthesis and Antibacterial Studies of a New Au(III) Complex with 6-Methyl-2-Thioxo-2,3-Dihydropyrimidin-4(1H)-One

This article describes the synthesis of a new metal complex using 6-methyl-2-thioxo-2,3-dihydropyrimidin-4(1H)-one. The compound was analyzed using several methods, including determining its melting point and employing UV-Vis, IR, ATR, 1H NMR, HSQC, and Raman spectroscopy for the free ligand. The metal complex was formed by combining aqueous solutions of metal salts with the ligand dissolved in DMSO and water, along with NaOH in a metal-to-ligand-to-base ratio of 1:4:2. The NMR signals of the ligand were assigned using 1H-1H COSY, DEPT-135, HMBC, and HMQC spectra. Furthermore, the compound’s antimicrobial activity against Gram-positive and Gram-negative bacteria, as well as yeasts, was assessed.

Less efficient skin penetration of the metal allergen Pd2+ compared to Ni2+ and Co2+ from patch test preparations.

Contrary to Ni2+- and Co2+-induced allergic contact dermatitis (ACD), reactions against Pd2+ are rare. However, Pd2+ activates a larger T cell fraction in vitro, suggesting an inefficient skin penetration. This study compares Ni2+, Co2+ and Pd2+ skin penetration from commonly used diagnostic patch test preparations (PTPs) and aqueous metal salt solutions. Using Franz diffusion cell assays, we applied the metals in PTPs (5% NiSO4, 1% CoCl2, 2% PdCl2 and 3% Na2PdCl4) and in solution to pigskin for 48 h, thereby mirroring the time frame of a patch test. The different compartments were analysed individually by inductively coupled plasma mass spectrometry. Metal ions were mainly retained in the upper stratum corneum layers. After application of PTPs, concentrations in the viable skin were lower for Pd2+ (1 and 7 μM) compared to Ni2+ and Co2+ (54 and 17 μM). Ni2+ and Co2+ penetrated the skin more efficiently than Pd2+ and thus may sensitize and elicit ACD more easily. This was observed for ions applied in petrolatum and aqueous solutions. We hypothesize that the differently charged metal complexes are responsible for the varying skin penetration behaviours.

Electrochemical Additive Manufacturing of Binary and Ternary Alloys at the Mircon Scale by Electrohydrodynamic Redox 3D Printing

The need for miniaturisation throughout many different industries brings classical subtractive manufacturing techniques to their limits. Additive manufacturing is able to overcome these limits which has made it a topic of interest in many scientific fields. This additional geometric freedom becomes increasingly important if feature sizes on the micron- or even nano-scale are desired. Multiple different techniques to fabricate device-grade metals at such length-scales have been reported [1]. As one of these techniques, electrohydrodynamic redox printing (EHD-RP) has shown promise to be a versatile fabrication tool [2, 3, 4] depositing dense, pure metallic structures at high deposition rates.In this contribution, we present our work on additively manufactured alloys. First, we introduce a novel EHD-RP approach using aqueous metal salt electrolytes instead of sacrificial anodes as ion sources. The use of metal salts not only expands the range of manufacturable metals, but also enables the fabrication of metal alloys with precise compositional control without the need for additives or a surplus of the less noble metal. We demonstrate this control by fabricating binary and ternary Cu-Ag, Cu-Zn and Cu-Ag-Zn alloys. The composition of the fabricated alloy exactly mirrors the composition of the aqueous metal salt solutions. These systems were chosen as a representative immiscible and miscible system, in order to study different growth mechanisms. Microstructural analysis of Cu-Ag alloys reveals the formation of a metastable mixed phase. Cu-Ag alloys were successively dealloyed to produce nano-porous Ag structures. The compositional control over the Cu-Ag alloy enables precise control of porosity in the dealloyed structures. These nano-porous Ag structures have also been tested as substrates for surface enhanced Raman spectroscopy.(1) L. Hirt, A. Reiser, R. Spolenak & T. Zambelli, Adv. Mater 2017, 29, 1604211(2) A. Reiser, M. Lindén, P. Rohner, A. Marchand, H. Galinski, A. S. Sologubenko, J. M. Wheeler, R. Zenobi, D. Poulikakos & R. Spolenak, Nat. Comm. 2019, 10, 1853(3) M. Nydegger, A. Pruška, H. Galinski, R. Zenobi, A. Reiser & R. Spolenak, Nanoscale 2022, 14, 17418(4) M. Menétrey, L. Koch, A. Sologubenko, S. Gerstl, R. Spolenak & A. Reiser, Small 2022, 18, 2205302

Electrohydrodynamic Redox Printing: A Swiss Army Knife of Metals Microfabrication?

The dissolution and deposition of metals in solvents is widely known and used in a large range of applications, from electroplating to electro-machining. More recently, it has also been used for additive manufacturing (AM) at the sub-micron scale, since electroplated metals offer as-deposited high-quality metals (in terms of porosity and contamination) compared to other small scale AM techniques [1,2]. These intricate, high-quality metal structures have a range of applications in microelectromechanical systems, photonics or micro-robotics. However, the nature of the deposition process requires a conductive substrate to provide the electrons necessary for the localized reduction of metal ions. This requirement renders the direct fabrication of microelectronic devices using electrochemical small scale AM a challenge, as often deposition on electrically insulating substrates is required.Here, we present our work on electrohydrodynamic redox printing (EHD-RP), an electrochemical small scale AM technique, and our efforts towards deposition on various substrates. We’ll first introduce EHD-RP with a focus on our recent work on the deposition from aqueous metal salt solutions onto conductive substrates. We’ll then discuss strategies to expand the concept of EHD-RP towards deposition on non-conductive substrates and how electrically floating structures can be fabricated. These strategies render EHD-RP a versatile technique for metals microfabrication.[1] M. Nydegger, A. Pruška, H. Galinski, R. Zenobi, A. Reiser and R. Spolenak. Additive Manufacturing of Zn with Submicron Resolution and its Conversion into Zn/ZnO core-shell structures. Nanoscale, 2022[2] L. Hirt, A. Reiser, R. Spolenak and T. Zambelli. Additive Manufacturing of Metal Structures at the Micrometer Scale. Adv. Mater., 29(17), 2017

Unraveling ultrasonic assisted aqueous-phase one-step synthesis of porous PtPdCu nanodendrites for methanol oxidation with a CO-poisoning tolerance

The tailored design of tri-metallic Pt-based porous nanodendrites (PNDs) is crucial for green energy production technologies, ascribed to their fancy features, great surface areas, accessible active sites, and stability against aggregation. However, their aqueous-phase one-step synthesis at room temperature remains a daunting challenge. Herein, we present a facile, green, and template-free approach for the one-step synthesis of PtPdCu PNDs by ultrasonication of an aqueous solution of metal salts and Pluronic F127 at 25 ℃, based on natural isolation among nucleation and growth step driven by the disparate reduction kinetics of the metals and acoustic cavitation mechanism of ultrasonic waves. The resultant PtPdCu PNDs formed in a spatial nanodendritic shape with a dense array of branches, open corners, interconnected pores, high surface area (46.9 m2/g), and high Cu content (21 %). The methanol oxidation reaction (MOR) mass activity of PtPdCu PNDs (3.66 mA/µgPt) is 1.45, 2.73, and 2.83 times higher than those of PtPd PNDs, PtCu PNDs, and commercial Pt/C, respectively based on equivalent Pt mass, which is superior to previous PtPdCu catalysts reported elsewhere, besides a superior durability and CO-poisoning tolerance. This study may pave the way for the controlled fabrication of ternary Pt-based PNDs for various electrocatalytic applications.

30 Reference Materials for the Measurement of Metals in Workplace Air

Abstract For the production of filters coated with metal oxides an aqueous metal salt solution is injected into a hydrogen/oxygen flame of a particle generator leading to the pyrolysis of the metal salts into nano-scaled metal oxide dust. The particles are introduced into a large sampling chamber (20 m³) via a dust tunnel (20 m). So far, the system was tested for Zn, Cu, Pb, Co, Ni, Mn and In but it should be suitable with all metals obtainable as soluble metal salts. For sample generation an eight-fold sampling system was developed for the GSP sampler. The constancy of the flow rate is assured by critical orifices. Up to fourteen of these systems can be operated to produce 112 samples in parallel. Nevertheless, for the production of a reference material a significantly higher number of samples will be needed. To achieve this aim the environmental conditions of the dust generation have to be stabilized for consecutive runs. The major problem was the temperature rise of the dust channel during the particle generation due to the heat of the flame. An additional heater was installed to work at a constant temperature of 30 °C. Three consecutive filter series were manufactured. The achieved temperature constancy of 30± 0.5 °C makes it possible to combine the successive filter series. The loadings of the combined series were Cobalt: 3.25±0.058 µg/filter, Nickel: 13.78±0.23 µg/filter, Lead: 109.5±3.0, Copper: 9.65 ±0.18 µg/filter and Zinc: 32.66±0.72 µg/filter.

ДИЗАЙН НАНОЧАСТИЦ ОКСИДОВ ПЕРЕХОДНЫХ МЕТАЛЛОВ С КОНТРОЛИРУЕМОЙ РАЗМЕРНОСТЬЮ

The paper presents generalized experimental data on the influence of synthesis conditions on the structural features of MeO transition metal oxide nanoparticles in a polymer matrix synthesized by chemical condensation. The synthesis process includes the interaction of aqueous solutions of metal salts of varying concentrations with alkalis in the presence of an aqueous solution of the natural polysaccharide arabinogalactan. Controlled growth of oxide nanoparticles was achieved by encapsulation of emerging NPs in a polysaccharide matrix. The structural properties of the obtained samples were analyzed using X-ray diffraction, IR and UV spectroscopy, and TEM and SEM electron microscopy.

Oxygenated Triazine-Heptazine Heterostructure Creates an Enormous Ascension to the Visible Light Photocatalytic Hydrogen Evolution Performance of Porous C3 N4 Nanosheets.

A highly efficient g-C3 N4 photocatalyst is developed by a novel one-pot thermal polymerization method under a salt fog environment generated by heating the aqueous solution of urea and mixed metal salts of NaCl/KCl, namely SF-CN. Thanks to the synergistic effect of the oxygenation and chemical etching of the salt fog, the obtained SF-CN is an oxygenated ultrathin porous carbon nitride with an intermolecular triazine-heptazine heterostructure, meanwhile, shows enlarged specific surface area, greatly enhanced absorption of visible light, narrowed band gap with a lower conduction band, and an increased photocurrent response due to the effective separation of photogenerated holes and electrons, comparing to those of pristine g-C3 N4 . The theoretical simulations further reveal that the triazine-heptazine heterostructure possesses better photocatalytic hydrogen evolution (PHE) capability than pure triazine and heptazine carbon nitrides. In turn, SF-CN demonstrates an excellent visible light PHE rate of 18.13mmolh-1 g-1 , up to 259.00 times of that of pristine g-C3 N4 .

Supercritical Hydrothermal Reactions for Material Synthesis

Abstract Since the early 1990s, Adschiri and his colleagues have performed research on the use of supercritical water in diverse applications, including heavy oil reforming, waste polymer decomposition and chemical raw materials recovery, cellulose hydrolysis and sugar recovery, lignin decomposition and chemical raw materials recovery, and nanoparticle synthesis. Regarding inorganic materials synthesis, they invented supercritical hydrothermal synthesis for the continuous flow synthesis of metal oxide nanoparticles, which has already found worldwide industrial applications. They proposed a two-fluid mixing flow system where an aqueous metal salt solution is mixed with supercritical water to heat the solution to the supercritical state within a very short time, that is not attainable by conventional reactor systems. Organic-inorganic hybrid nanoparticles synthesis was demonstrated in the supercritical state, realizing homogeneous phase formation of organic molecules at high loadings. By optimizing the reaction conditions, small facet-controlled nanoparticles with narrow particle size distribution can be obtained. Organic modification of nanoparticles is shown to be effective for fabricating highly concentrated nanohybrid polymers or nano inks. Furthermore, these synthesized facet-controlled nanoparticles show high catalytic activities. Indeed, it is demonstrated that steam reforming of heavy oils or biomass wastes (black liquor) can occur in water even at low temperatures.

One-Step Synthesis of Functional Sulfonated Polynaphthoylenebenzimidazoles for Biosensing Applications

Polynaphthoylenebenzimidazoles containing functional sulfo groups were synthesized by a one-step method in a sulfuric acid medium with oleum. A polymer-analogous transformation of these polymers with aqueous solutions of metal salts (K, Ca, and Cr) was carried out. Their chemical structure was characterized by FTIR, NMR, and elemental analysis. Polymer salt coatings were deposited on QCM sensor surfaces by electron beam-induced vacuum deposition. The morphology of the coatings was characterized by AFM. It was shown that the coatings formed from a series of polymer salts have different adsorption activity in acetaminophen–water solution compared to distilled water. The QCM results indicate that sensor signal correlates with polymer coating thickness, morphology, and its chemical composition.

Separation of chitin from shrimp shells enabled by transition metal salt aqueous solution and ionic liquid

Chitin is a widely used important industrial polymer mainly from shrimp shells, but its commercial preparation is under the great challenge of serious pollution due to the requirement of HCl and NaOH. Herein, we demonstrated that high purity chitin can be obtained from waste shrimp shells (WSSs) by cascade separation with transition metal salt aqueous solution and ionic liquid (IL). Firstly, calcium carbonate of WSSs was effectively removed in the metal salt aqueous solution driven by the ion exchange interaction. Subsequently, 1-butyl-3-methylimidazolium chloride ([Bmim]Cl) had bifunctional abilities to remove residual protein and introduced metal salts simultaneously by hydrogen bonding and coordination interactions. The key experimental factors affecting the separation process were systematically studied, including the type of metal salts, temperature, and [Bmim]Cl loading. After sequential treatment with a 20 %(mass) NiSO 4 aqueous solution at 130 °C and [Bmim]Cl at 150 °C, the purity of α-chitin can be up to 96.5 %(mass) that meets commercial requirements. The use of metal salts with higher coordination ability makes the preparation of chitin no longer depend on the commonly acid-base reaction, which is conducive to the preservation of chitin structure.

Continuous Flow Synthesis of Cd1-x Znx S and CdS/ZnS Core/Shell Semiconductor Nanoparticles by MicroJet Reactor Technology.

From aqueous precursor solutions of metal salts and sodium sulfide using MicroJet Reactor (MJR) technology Cd1-x Znx S and CdS/ZnS core/shell semiconductor nanoparticles were synthesized. The MJR approach represents an automated, continuous, flexible and scalable route for nanoparticle synthesis, providing a tight control over process parameters and thus simple size, shape and composition control. Since particle sizes below the excitonic Bohr radius were obtained by MJR, the nanoparticulate materials exhibit quantum confinement effects. By varying the precursor ratio the band gap of Cd1-x Znx S Quantum Dots (QDs) could be targeted from 3.1 to 3.6 eV. CdS/ZnS core/shell QDs were prepared by enclosing CdS particles from MJR with ZnS produced by thermal decomposition of a Zn-MPA complex. Adjustment of the shell thickness increased the photoluminescence intensity by 43 %. Synthesis of ternary sulfides in the form of core/shell particles broadens the spectrum of materials accessible by MJR and demonstrates the extraordinary flexibility of the technology.

In-situ enhanced laser absorption in aqueous transition metal salt solution enables high-quality backside wet etching of optical glass by near-infrared lasers

A laser-induced backside wet etching technique using near-infrared laser sources (N-LIBWE) has been proposed for high-quality micromachining of optical glass. Compared with conventional LIBWE using organic dye solutions with high absorption coefficients (∼104–105 cm−1) as the liquid absorbent, the transition metal salt solution used in N-LIBWE shows the absorption coefficient of only 10-1-101 cm−1. Moreover, as we proved in this study, the etching rate of N-LIBWE is independent of the absorptivity of the liquid absorbent. How the etching occurs during N-LIBWE is still controversial. Herein, interface images with a temporal resolution of 4 ns after the start of laser irradiation are captured by a stroboscopic shadowgraphy system. Afterward, the density, pressure, and temperature distribution in the solution are calculated by a physics-based two-dimensional hydrodynamic model to explain the observed interface images. We prove that the localized laser absorption is enhanced with laser irradiation because of the in-situ formation of solid substances. It is the properties of the formed solid products instead of the normal absorption coefficient of the solution that determines the final interface status. We further prove that the formed solid substances in aqueous CuSO4 solutions are primarily amorphous nanoclusters, which benefit the enhancement of laser absorption and tend to attach to the transparent substrates, resulting in the incubation effect in N-LIBWE. Our results provide systematic mechanisms explaining the N-LIBWE process, which also benefit the deep understanding of other liquid-assisted laser materials processing technologies.

In Situ Diagnostics and Role of Light‐Induced Forces in Metal Laser Nanoprinting

AbstractCompared to 3D laser nanoprinting of polymers, the mechanisms in laser nanoprinting of metals are rather poorly understood. For the example of platinum investigated here, the printing process starts with the formation of metal nanoparticles by photo‐reduction of metal salts in aqueous solution in a diffraction‐limited laser focus. To investigate the printing process in situ, a weak continuous‐wave probe laser is co‐focused in addition to the focused femtosecond printing laser. The light of the probe laser is backscattered off the emerging metal structures, and recorded with a temporal resolution of 1 µs. It is found that the formed metal nanoparticles are quickly ejected from the focus on a timescale of some 10 µs. Once a nanoparticle randomly adheres to the substrate surface, it serves as a seed from which structures can be built‐up. The following nanoparticles are sintered onto that seed to form a metallic voxel on a timescale of some 10 ms. By polarization‐dependent experiments and full‐wave optical simulations, it is shown that light‐induced forces onto the nanoparticles play a significant role. The improved understanding of the microscopic processes in metal nanoprinting is a prerequisite for further process optimizations and applications, for example in terms of printed optoelectronics.