Electrodeposition of Soft Magnetic Fe-W-P Alloy Coatings from an Acidic Electrolyte

Fe-W-P coatings were deposited from a newly developed electrolytic bath. The effect of plating parameters, such as electrolyte current density and pH has been studied. It was found that\ua0the pH has a very strong effect on the phosphorous content of the coatings. Metallic-like, non-powdery alloys of Fe-W-P deposits with no cracks (lowly stressed) can be obtained at a lower pH\ua0(<3), exhibiting high phosphorus (up to 13 at.%) and low tungsten (6 at.%) contents. At a higher pH\ua0(>3), the composition changes to low phosphorus and high tungsten content, showing a matte,\ua0greyish, and rough surface. The applied current density also influences the morphology and the\ua0amount of phosphorous content. The deposits showed an amorphous structure for all samples with\ua0soft ferromagnetic properties

Hot electron electrochemistry at silver activated by femtosecond laser pulses

A silver microelectrode with a diameter of 30 µm in an aqueous K2SO4 electrolyte was irradiated with 55 fs and 213 fs laser pulses. This caused the emission of electrons which transiently charged the electrochemical double layer. The two applied pulse durations were significantly shorter than the electron-phonon relaxation time. The laser pulse durations had negligible impact on the emitted charge, which is incompatible with multiphoton emission. On the other hand, the observed dependence of emitted charge on laser fluence and electrode potential supports the thermionic emission mechanism

Alkoxylated β-Naphthol as an Additive for Tin Plating from Chloride and Methane Sulfonic Acid Electrolytes

Beta-naphthol was one of the first additives introduced for smooth and homogeneoustin electrodeposition. Although it can be oxidized under the plating conditions, forming either1,2-napthoquinone or polymeric materials based on naphthioxides, it is still in use. In this work,an investigation of its more stable form, alkoxylated beta-naphthol (ABN), on tin plating is undertaken.For this purpose, chloride based (pH ~5) and methane sulfonic acid (MSA, pH ~0.5) electrolytes,including ABN, were prepared. Reaction kinetics were studied by polarization, Tafel measurements,and cyclic voltammetry. Tin electrodeposits were obtained on flat brass substrates. Surfacemorphology and preferred crystal orientation were studied by Scanning Electron Microscopy (SEM)and X-ray Diffraction (XRD). In both studied electrolytes ABN acts as an inhibitor but in the case ofthe chloride electrolyte it is more pronounced. In the MSA electrolyte this effect was overlaid by thepresence of tin-citrate complexes. In the chloride-based electrolyte, ABN has a grain refining effect,while in the MSA electrolyte an increase of ABN concentration leads to a slight enlargement of theaverage grain size. X-ray analysis shows a constant decrease of the (101) intensity with increasingconcentration of ABN for the sample deposited from both baths

Femtosecond laser generation of bimetallic oxide nanoparticles with potential X-ray absorbing and magnetic functionalities for medical imaging applications

Bimetallic nanoparticles have gained vivid attention due to their unique and synergistic properties. They can be used in fields such as solar cells, optics, sensing, as well as medicine. The generation of bimetallic nanoparticles, containing oxide phases of both magnetic and X-ray attenuating metals for bioimaging applications has been challenging with traditional chemical synthesis methods. An alternative is the generation of nanoparticles from binary oxide ceramics by laser ablation in liquid. However, the applicability of this technique for production of hybrid nanoparticles consisting of magnetic and X-ray absorbing elements has not been demonstrated yet. In this work, novel ceramics composed of bimetallic oxide phases of iron-tantalum, iron-tungsten, and ironbismuth were produced by a reaction-sintering method. The bulk samples were characterized with scanning electron microscopy, energy dispersive X-ray spectroscopy, and X-ray diffractometry. Nanoparticles were produced in aqueous and ethanol solutions by employing a femtosecond laser and characterized with transmission electron microscopy, selected area electron diffraction, and energy dispersive X-ray spectroscopy. The results demonstrated that the production of binary oxide bulk ceramics and their subsequent laser ablation in liquids leads to the successful generation of bimetallic oxide nanoparticles, without a core-shell morphology. In addition, it was found that the ablation threshold fluence of bulk samples as well as the crystallinity of the synthesized nanoparticles is governed by both the nature of the metallic oxide ceramics and the employed liquid. The results pave the way for a single step generation of well-defined bimetallic nanoparticles by laser ablation that could potentially exhibit X-ray and magnetic absorption properties suitable for multimodal imaging applications.This research has been partially funded by the Spanish Ministerio de Ciencia e Innovacion through the research project MAT2015-67354R (MINECO-FEDER). Funding through a Marie Sklodowska-Curie Individual Fellowships (MSCA-IF 2014, 656908-NIMBLIS-ESR) of the Horizon 2020 program, and the Project PI-0030-2017 of the Junta de Andalucia in the framework of the integrated territorial initiative 20142020 for research and innovation in biomedicine and health sciences in the province of Cadiz is also greatly appreciated. The authors acknowledge support for scanning electron microscopy by Dr. Stephan Puchegger and the faculty center for nanostructure research at the University of Vienna

Pursuit of optimal synthetic conditions for obtaining colloidal zero-valent iron nanoparticles by scanning pulsed laser ablation in liquids

Liquid-Assisted Pulsed Laser Ablation (LA-PLA) is a promising top-down method to directly synthesize colloidal dispersions of nanoparticles in a eco-friendly manner. However, the role of LA-PLA synthesis parameters is not yet fully agreed. This work seeks to optimize the production of nanoscale zero-valent iron (nZVI) particles suitable for biomedical or environmental applications using nanosecond LA-PLA on iron targets with different ablation media, laser and target scanning parameters. The use of alcohols as solvents produces iron-iron oxide core-shell nanoparticles with amorphous cores, except for a small crystalline fraction corresponding to the biggest core sizes. Decreasing carbon chain length and complexity leads to a thinning of the carbonaceous material coatings and an increase of the colloidal stability and the nanoparticle productivity. Moreover, a decrease of solvent density and surface tension allows obtaining reduced sizes and polydispersity values. Among, laser and scanning parameters, the pulse accumulation per spot displayed a clear effect in boosting size and productivity. As main outcome, aqueous dispersions with suitable colloidal properties are obtained, either by transferring to water of optimized nZVI particles produced in ethanol, or by direct formation of nZVI particles and in situ coating with hydrophilic molecules in aqueous solutions of these moleculesThis research has been funded by the Spanish Ministry of Economy and Competitiveness (MINECO) and FEDER [research projects MAT2015-67354R, MAT2014-53961-R, and MAT2017- 86826-R] and by the Aragón government (DGA) [grant for consolidated group PLATON E31_17R]. OBM thanks the financial support from the “Ramón y Cajal Program” [research project RYC2010-07332] of the Spanish Ministry of Economy and Competitiveness (MINECO) and the H2020 Action H2020-MSCA-IF-2014_ST [grant 656908-NIMBLIS] of the Executive Agency for Research Manages of EU Commissio

Subwavelength Nanostructuring of Gold Films by Apertureless Scanning Probe Lithography Assisted by a Femtosecond Fiber Laser Oscillator

Optical methods in nanolithography have been traditionally limited by Abbe’s diffraction limit. One method able to overcome this barrier is apertureless scanning probe lithography assisted by laser. This technique has demonstrated surface nanostructuring below the diffraction limit. In this study, we demonstrate how a femtosecond Yb-doped fiber laser oscillator running at high repetition rate of 46 MHz and a pulse duration of 150 fs can serve as the laser source for near-field nanolithography. Subwavelength features were generated on the surface of gold films down to a linewidth of 10 nm. The near-field enhancement in this apertureless scanning probe lithography setup could be determined experimentally for the first time. Simulations were in good agreement with the experiments. This result supports near-field tip-enhancement as the major physical mechanisms responsible for the nanostructuring

Lasers in the Conservation of Artworks

Within the last decades, the use of lasers in artworks conservation became an important tool for many conservators, scientists, architects and other experts, who are involved in the care of monuments and artefacts or laser technology. For the first time in 1995 Professor Costas Fotakis brought together restorers and scientists to discuss the potential of lasers in art conservation. Since then the field of "Lasers in the Conservation of Artworks" has gained enormously in importance. Nowadays restorers and laser scientists work close together in order to develop new fields of applications during the last years. Furthermore a large number of national and international research projects have been carried out by conservator-restorers, architects and scientists. In the last 10 years a number of historical and artistic high quality monuments (e.g. St. Stephens Cathedral in Vienna) have been cleaned or measured by laser and brought the laser in the spectra of tools which are useful in the sensible field of artworks. The proceedings of the congress addresses scientists, conservator-restorers, companies, architects, decision-makers and other experts involved in conservation projects or in the research of new laser equipment