Pulsed Laser Ablation In Water Research Articles

Surface Nanostructures Composed of Thiolated Cyclodextrin/Au and Fe Species: Gas- and Liquid-Phase Preparation.

Supramolecular surface nanostructures have application potential as functional devices. The complex combination of thiolated cyclodextrin, chemisorbed on an Au surface (Au-S-CD), with deposited Fe species is studied by secondary ion mass spectrometry. The Fe species are prepared by pulsed laser ablation in water and thermal effusion in vacuum. Using laser ablation in water, the solution of Fe species is dropped on Au-S-CD, where mass peaks at 1227 m/z, 1243 m/z, and 1260 m/z are observed and assigned to C42 H68 O34 SNa-Fe(+) , C42 H68 O34 SK-Fe(+) together with C42 H68 O34 SNa-FeO(+) , and C42 H68 O34 SK-FeO(+) , respectively. On the other hand, laser ablation directly linked to the Au-S-CD surface results in desorption of CD-S. Thermal effusion, even with a cooled surface, was negative with respect to the complex observation. Laser ablation results in the formation of a supramolecular host-guest complex of the form Au-S-CD-Fe, and in the formation of an adduct of the form Au-S-CD-FeO.

Synthesis of oxocarbon-encapsulated gold nanoparticles with blue-shifted localized surface plasmon resonance by pulsed laser ablation in water with CO2 absorbers

Colloidal suspensions of oxocarbon-encapsulated gold nanoparticles have been synthesized in a one-step procedure by pulsed-laser ablation (PLA) at 532 nm of a solid gold target placed in aqueous solution containing CO2 absorbers, but without any stabilizing agent. Multi-wavelength surface enhanced Raman spectroscopy allows the identification of adsorbed amorphous carbon and graphite, Au-carbonyl, Au coordinated CO2-derived bicarbonates/carbonates and hydroxyl groups around the AuNPs core. Scanning electron microscopy, energy dispersive x-ray analysis and high resolution transmission electron microscopy highlight the organic shell structure around the crystalline metal core. The stability of the colloidal solution of nanocomposites (NCs) seems to be driven by solvation forces and is achieved only in neutral or basic pH using monovalent hydroxide counter-ions (NaOH, KOH). The NCs are characterized by a blue shift of the localized surface plasmon resonance (LSPR) band typical of metal-ligand stabilization by terminal π-back bonding, attributed to a core charging effect caused by Au-carbonyls. Total organic carbon measurements detect the final content of organic carbon in the colloidal solution of NCs that is about six times higher than the value of the water solution used to perform PLA. The colloidal dispersions of NCs are stable for months and are applied as analytical probes in amino glycoside antibiotic LSPR based sensing.

One-step preparation of YVO4:Eu3+ nanoparticles by pulsed laser ablation

YVO4:Eu3+ nanoparticles were prepared via pulsed laser ablation in water and sodium dodecyl sulfate solution. The particle phase, morphology, and optical properties were evaluated by XRD, TEM, SEM, and PL. Ovoid-like nanoparticles having an average diameter of 97 nm were prepared in water, whereas nearly spherical nanoparticles with an average diameter of 55 nm were obtained in sodium dodecyl sulfate solution. The photoluminescence properties of the YVO4:Eu3+ nanoparticles were affected by the defects in the nanoparticles, as demonstrated by HR-TEM and recovered after annealing at 600 °C for 24 h. Fourier transform infrared spectroscopy revealed that the surfaces of the nanoparticles obtained in sodium dodecyl sulfate solution were covered by surfactant molecules, leading to smaller nanoparticles. These results also provide contributions for the synthesis of oxide nanoparticles in the domain of laser ablation in liquid as single-phase YVO4 was obtained in this study.

Creation of ZnS nanoparticles by laser ablation in water

We have created ZnS nanoparticles using pulsed laser ablation of ceramic target in water with an aim to produce nanoparticles with uniform distribution of the size. The particle size, structure, and physical properties were systematically investigated by X-ray diffraction (XRD), Raman spectra, high-resolution transmission electron microscopy (HRTEM), selected area electron diffraction (SAED), and energy-dispersive spectroscopy. The ZnS nanoparticles were confirmed from XRD, Raman and SAED patterns to possess the sphalerite structure. Chemical composition of the ZnS nanoparticles was found to be stoichiometric. HRTEM images exhibited well-arranged lattices with the space of 0.274 nm for (200) plane and that of 0.317 nm for (111) plane. The present results demonstrate that pulsed laser ablation in water is effective and promising to create nanoparticles with controllable size in a large scale.

Highly-repeatable generation of very small nanoparticles by pulsed-laser ablation in liquids of a high-speed rotating target

By irradiating a cylindrical silver target rotated at a high-speed within the range 300-2400 rpm (lateral speed 0.16-1.25 m s-1) in pure water, we prepare ligand-free Ag nanoparticles (NPs) with a size of 4 ± 2 nm which are likely to be primary particles. Usually, the generation of NPs showing such a small size requires either a laser post-treatment and/or chemical additives. As the rotation rate of the target is increased, calculated 3D flow patterns revealed different hydrodynamic regimes which clearly influence the ablation rate and repeatability of the process as well as the colloidal properties. In addition to revealing the importance of fluid dynamics in pulsed-laser ablations in liquids, this study provides a way for producing in one step pure NPs with sizes below 5 nm which are suitable for applications in catalysis.

Ag@Au core–shell nanoparticles synthesized by pulsed laser ablation in water: Effect of plasmon coupling and their SERS performance

Ag@Au core–shell nanoparticles are synthesised by pulsed laser ablation in water using low energy laser pulses. The plasmon characteristics of these core–shell nanoparticles are found to be highly sensitive to the thickness of Au coating. In the synthesis, at first silver nanocolloid was prepared by ablating Ag target and then it is followed by ablation of Au target for different time durations to form Ag@Au core–shell nanostructures. The effect of plasmon–plasmon coupling on the absorption spectra is investigated by decreasing the effective distance between the nanoparticles. This is achieved by reducing the total volume of the colloidal suspension by simple evaporation of water, the solvent used. The suitability of these core–shell nanostructures for application as surface enhanced Raman scattering substrates are tested with crystal violet as probe molecules. Influence of plasmon coupling on the enhancement of Raman bands is found to be different for different bands.

Ag nanoparticles obtained by pulsed laser ablation in water: surface properties and SERS activity

We studied the surface properties and reactivity of silver nanoparticles obtained by picosecond or nanosecond pulsed laser ablation in water and with 1064‐nm wavelength. Ultraviolet–visible spectroscopy results and subsequent modelling by Mie theory indicated the presence of an oxide layer on the nanoparticle surface, which favours the colloidal stability, but reduces the interaction with the environment. The oxide layer is also responsible for the reduced surface enhanced Raman spectroscopy (SERS) activity of these colloids with respect to those obtained by chemical reduction. However, SERS activation can be efficiently obtained by addition of chloride ions to the colloids, leading to SERS enhancement factors that are comparable with those of the chemically prepared counterparts. Copyright © 2015 John Wiley & Sons, Ltd.

Deep Ultraviolet Emission from Water-Soluble SnO2 Quantum Dots Grown via a Facile “Top-Down” Strategy

Tin oxide (SnO 2 ) is a promising wide bandgap semiconductor for next generation ultraviolet (UV) non-polar optoelectronic devices applications. The development of SnO 2 -based optoelectronic devices is obsessed by its low exciton emission efficiency. In this study, quantum confined SnO 2 nanocrystals have been fabricated via pulsed laser ablation in water. The SnO 2 quantum dots (QDs) possess high performance exciton emission at 297–300 nm light in water. The exciton emission intensity and wavelength can be slightly tuned by laser pulse energy and irradiation time. Optical gain has been observed in SnO 2 QDs. Therefore, SnO 2 QDs can be a promising luminescence material for the realization of deep UV nano-emitter and lasing devices.

Dopamine and ascorbic acid electro-oxidation on Au, AuPt and Pt nanoparticles prepared by pulse laser ablation in water

ABSTRACT In this study, we have investigated the use of PtAu alloy nanoparticles (NPs) with four different compositions (from x = 0 to 100) as electrodes for the detection of dopamine (DA) in the presence of ascorbic acid (AA). The Au 100-x Pt x NPs were prepared by pulsed laser ablation in an alkaline solution without using any surfactants or capping agents. The diameter of the particle ranges from 2.5 nm for pure Pt to 5.2 nm for pure Au NPs. Cyclic voltammetry showed that the number of DA molecules being oxidized on the NPs surface decreases with the Au content (from 9.0 × 10 −11 mol on Au to 4.8 × 10 −11 mol on Pt NPs), which emphasizes the preponderant role of Au surface sites on the electrochemical oxidation of DA. On the other hand, the oxidation current of AA is greatly enhanced by alloying Au with Pt, and the peak current of the alloyed NPs is about two (Au 50 Pt 50 ) and four times (Au 70 Pt 30 ) higher than that of Au NPs. It is suggested that the oxidation of the lateral chain of AA on the Pt sites occurs simultaneously to the oxidation of the ascorbate anion to dehydro ascorbic acid on the Au sites. Finally, it was shown by differential pulse voltammetry that Au and Au 100-x Pt x NPs can detect DA in solutions containing AA with a concentration 1000× higher. For example, for Au 70 Pt 30 the sensitivity and detection limit for the detection of DA in presence of 2 mM AA were 3.34 μA μM −1 and 0.06 μM (at S/N = 3) respectively, essentially the same values (3.50 μA μM −1 cm −2 and 0.05 μM) as in the absence of AA.

Ag nanoparticles formed by femtosecond pulse laser ablation in water: self-assembled fractal structures

We report for the first time on the formation of self-assembled fractals of spherical Ag nanoparticles (Nps) fabricated by femtosecond pulse laser ablation of a solid silver target in water. Fractal structures grew both in two and three Euclidean dimensions (d). Ramified-fractal assemblies of 2 nm height and 5–14 μm large, decorated with Ag Nps of 3 nm size, were obtained in a 2d geometry when highly diluted drops of colloidal suspension were dried at a fast heating rate over a mica substrate. When less-diluted drops were dried at slow heating rate, isolated single Nps or rosette-like structures were formed. Fractal aggregates about 31 nm size in 3d geometry were observed in the as-prepared colloidal suspension. Electron diffraction and optical extinction spectroscopy (OES) analyses performed on the samples confirmed the presence of Ag and Ag2O. The analysis of the optical extinction spectrum, using the electrostatic approximation of Mie theory for small spheres, showed the existence of Ag bare core, Ag–Ag2O and air–Ag core–shell Nps, Ag–Ag2O being the most frequent type [69 % relative abundance (r.a.)]. Core-size and shell-thickness distribution was derived from OES. In situ scattering measurements of the Ag colloidal suspension, carried out by small-angle X-ray scattering, indicate a mass fractal composed of packaged 〈D SAXS〉 = (5 ± 1) nm particles and fractal dimension d f = 2.5. Ex situ atomic force microscopy imaging displayed well-ramified structures, which, analyzed with box-counting method, yield a fractal dimension d f = 1.67. The growing behavior of these 2d and 3d self-assembled fractals is consistent with the diffusion-limited aggregation model.

(hkl)-Specific defects of MgO–CoO alloy produced by pulsed laser ablation in water

MgO–CoO particles with (hkl)-specific paracrystalline defects by pulsed laser ablation of solid-solution powders in water.

Engineering the intermediate band states in amorphous Ti3+-doped TiO2 for hybrid dye-sensitized solar cell applications

Generation of an intermediate band state in amorphous TiO2 by ultraviolet pulsed laser ablation in water.

Reduced aggregation and cytotoxicity of amyloid peptides by graphene oxide/gold nanocomposites prepared by pulsed laser ablation in water.

A novel and convenient method to synthesize the nanocomposites combining graphene oxides (GO) with gold nanoparticles (AuNPs) is reported and their applications to modulate amyloid peptide aggregation are demonstrated. The nanocomposites produced by pulsed laser ablation (PLA) in water show good biocompatibility and solubility. The reduced aggregation of amyloid peptides by the nanocomposites is confirmed by Thioflavin T fluorescence and atomic force microscopy. The cell viability experiments reveals that the presence of the nanocomposites can significantly reduce the cytotoxicity of the amyloid peptides. Furthermore, the depolymerization of peptide fibrils and inhibition of their cellular cytotoxicity by GO/AuNPs is also observed. These observations suggest that the nanocomposites combining GO and AuNPs have a great potential for designing new therapeutic agents and are promising for future treatment of amyloid-related diseases.

Processing conditions in pulsed laser ablation of gold in liquid for fabrication of nanowire networks

The experimental conditions were investigated enabling one to fabricate Au nanowire networks by pulsed laser ablation in water. The study revealed that it is possible to produce alternatively nanoparticles (or aggregates) or nanowire networks at certain wavelengths depending on the laser fluence. An Au disc immersed in double-distilled water was used as a target. The second (λSHG=532nm) and the third (λTHG=355nm) harmonics of a Nd:YAG laser system were utilized to produce different Au colloids. The values of the laser fluence for both wavelengths under the experimental conditions chosen were varied from several J/cm2 to tens of J/cm2. The optical extinction spectra of the colloids in the UV/vis region were obtained to evaluate the structure of the dispersed Au phase. Transmission electron microscopy (TEM) was applied to visualize the size and morphology of the colloidal particles. Their structure and phase composition were studied by high-resolution transmission electron microscopy (HRTEM) and selected area electron diffraction (SAED) and used to make an assumption on how they had been formed.

Effect of electric field on the properties of bismuth oxide nanoparticles prepared by laser ablation in water

In this work, preparation and characterization of α-Bi2O3 by pulsed laser ablation in water under effect of electric field is presented. UV–visible measurements showed that a red shift in the absorption spectra of Bi2O3 nanoparticles (NPs) was observed when the electric field increased. Applying electric field during laser ablation of Bi2O3 led to increasing the particle size. The morphological investigation, carried out using atomic force microscope, showed that the root mean square roughness and the grain sizes of Bi2O3 NPs are increase after applied of the electric field. Energy dispersive X-ray investigations confirm the complete oxidation of ablated bismuth after applying of electric field. X-ray diffraction patterns revealed that the structure of Bi2O3 remained polycrystalline with small diffraction intensity around (102) plane after applying of electric field.

Palladium nanoparticles produced by CW and pulsed laser ablation in water

Palladium nanoparticles are receiving important interest due to its application as catalyst. In this work Pd nanoparticles have been obtained by ablating a Pd target submerged in de-ionized using both, pulsed as well as continuous wave (CW) laser. The influence of laser parameters involved in the formation in nanoparticles has been studied. Crystalline phases, morphology and optical properties of the obtained colloidal nanoparticles were characterized by means of transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM) and UV/vis absorption spectroscopy. The obtained colloidal suspensions consisted of pure Pd nanoparticles showing spherical shape with diameters ranging from few nanometers to 5–60nm. The moderate irradiance delivered by the CW laser favours high production of uniform nanoparticles.

Luminescent silicon nanocrystals produced by near-infrared nanosecond pulsed laser ablation in water

We report the investigation of luminescent nanoparticles produced by ns pulsed Nd:YAG laser ablation of silicon in water. Combined characterization by AFM and IR techniques proves that these nanoparticles have a mean size of ∼3nm and a core–shell structure consisting of a Si-nanocrystal surrounded by an oxide layer. Time resolved luminescence spectra evidence visible and UV emissions; a band around 1.9eV originates from Si-nanocrystals, while two bands centered at 2.7eV and 4.4eV are associated with oxygen deficient centers in the SiO2 shell.

Laser-induced synthesis of silver nanoparticles and their conjugation with protein

Partially oxidized spherical silver nanoparticles (AgNPs) of different size are prepared by pulsed laser ablation in water and directly conjugated to protein S-ovalbumin for the first time and characterized by various optical techniques. UV–Visible spectrum of AgNPs showed localized surface plasmon resonance (LSPR) peak at 396 nm which red shift after protein addition. Further the increased concentration of AgNPs resulted a decrease in intensity and broadening of S-ovalbumin peak (278 nm), which can be related to the formation of protein NPs complex caused by the partial adsorption of S-ovalbumin on the surface of AgNPs. The red shift in LSPR peak of AgNPs after mixing with S-ovalbumin and decrease in protein-characteristic peak with increased silver loading confirmed the formation of protein–AgNPs bioconjugates. The effect of laser fluence on the size of AgNPs and nanoparticle–protein conjugation in the size range 5–38 nm is systematically studied. Raman spectra reveal broken disulphide bonds in the conjugated protein and formation of Ag–S bonds on the nanoparticle surface. Fluorescence spectroscopy showed quenching in fluorescence emission intensity of tryptophan residue of S-ovalbumin due to energy transfer from tryptophan moieties of albumin to AgNPs. Besides this, small blue shift in emission peak is also noticed in presence of AgNPs, which might be due to complex formation between protein and nanoparticles. The binding constant (K) and the number of binding sites (n) between AgNPs and S-ovalbumin have been found to be 0.006 M−1 and 7.11, respectively.

Self-Organized Micro-Columns and Nano-Spheres Generated by Pulsed Laser Ablation of Ti/Al Alloy in Water

Dense arrays of micro-columns are formed on the surface of Ti-Al alloy by cumulative nanosecond pulsed laser ablation in water. The fabric-like structure characterized by Ti-Al nano-spheres absorbed on micro-cluster in liquid is most likely responsible for the occurrence of laser micro-etching and localized melting, resulting in continuous deepening of micro-holes and the formation of micro-columns. Laser induced plasma spectroscopy is carried out to reveal the effect of micro-columns on subsequent pulse laser ablation. The intensity of spectral lines from Ti ions by additional laser ablation of the modified spot is higher than that created over a smooth surface. These results suggest that the micro-columns lead to an enhanced absorption of the following laser energy. The proposed results and relevant discussions are of importance for the development of light-trapping coatings on a metal surface.

Green synthesis of selenium nanoparticles by excimer pulsed laser ablation in water

Pure selenium nanoparticles were successfully synthesized by Liquid Phase - Pulsed Laser Ablation (LP-PLA) in de-ionized water. Excimer laser (248 nm) operating at low fluence (F ∼ 1 J/cm2) was used to generate colloidal solutions of selenium nanoparticles. The obtained selenium nanoparticles were characterized by UV-visible spectroscopy, Raman spectroscopy, Dynamic Light Scattering, and Transmission Electron Microscopy. We describe the multi-modal size distributions generated and use the centrifugation method to isolate the smallest nanoparticles (∼60 nm in diameter).