Pulsed Laser Ablation In Water Research Articles

Unexpected Electronic Features of NiO Quantum Dots Produced by Femtosecond Pulsed Laser Ablation in Water.

This study examines the effect of quantum confinement and surface orientations on the electronic properties of NiO quantum dots. It compares NiO nanocrystals produced via atmospheric-pressure microplasma and femtosecond laser (fs-laser) ablation in water, finding that both methods yield quantum-confined nanocrystals with a defined face-centered cubic lattice. Notably, fs-laser synthesis generates crystalline nanocrystals from both crystalline and amorphous targets. While the electronic properties, i.e., energy of the highest occupied molecular orbital and lowest unoccupied molecular orbital (LUMO), of microplasma-synthesized NiO nanocrystals are consistent with the literature, the electronic characteristics of NiO nanocrystals produced by a fs-laser, particularly the high-lying LUMO level, are unusual for NiO quantum dots. Supported by density functional theory calculations, we show that the observed level positions are related to the different polar and nonpolar faces of the nanocrystal surface.

A comprehensive investigation of structural, optical, morphological, and electrical properties of CuO-NPs synthesized by pulsed laser ablation in water: effect of laser fluence

A comprehensive investigation of structural, optical, morphological, and electrical properties of CuO-NPs synthesized by pulsed laser ablation in water: effect of laser fluence

Green synthesis of blue titania nanoparticles by pulsed laser ablation in water

This work aimed at using pulsed laser ablation in water (PLAW) for the production of titanium dioxide nanoparticles in water from a commercially pure titanium target. There is great commercial interest in nanotitania, which can be found in products including paints, coatings, textiles, cosmetics, solar panels, and catalysts. Nevertheless, nanotitania is usually obtained through chemical routes, which are cost-intensive and cause a negative environmental impact. PLAW comes as a cleaner option for obtaining nano-TiO2 since it uses only solid titanium and deionized water as raw materials. After the process, an optical micrography of the Ti targets was carried out to assess the interaction of the laser with the metallic surface. The nanoparticles were characterized by DLS, TEM, Raman, XRD, and UV–Vis. Nano-TiO2 activity as a photocatalyst was tested for the degradation of the dye RR141. TEM images point to two populations of produced nanoparticles: one spherical with average sizes between 8 and 13 nm, and one spindle-like with the major axis average ranging between 17 and 35 nm. Composition analyses with XRD and Raman indicate the formation of anatase, rutile, and amorphous titania. The color of the solution produced was bluish, which may indicate the presence of surface defects that extend the light absorption band to the visible range. The catalysis experiments showed suitable results for the UV spectrum, and the calculated bandgaps were close to that of anatase, around 3.2 eV.

Structural, morphological and optical properties of tungsten trioxide nanoparticle synthesis by pulsed laser ablation in water: effect of laser fluence

Structural, morphological and optical properties of tungsten trioxide nanoparticle synthesis by pulsed laser ablation in water: effect of laser fluence

Boron Nanoparticle-Enhanced Proton Therapy for Cancer Treatment.

Proton therapy is one of the promising radiotherapy modalities for the treatment of deep-seated and unresectable tumors, and its efficiency can further be enhanced by using boron-containing substances. Here, we explore the use of elemental boron (B) nanoparticles (NPs) as sensitizers for proton therapy enhancement. Prepared by methods of pulsed laser ablation in water, the used B NPs had a mean size of 50 nm, while a subsequent functionalization of the NPs by polyethylene glycol improved their colloidal stability in buffers. Laser-synthesized B NPs were efficiently absorbed by MNNG/Hos human osteosarcoma cells and did not demonstrate any remarkable toxicity effects up to concentrations of 100 ppm, as followed from the results of the MTT and clonogenic assay tests. Then, we assessed the efficiency of B NPs as sensitizers of cancer cell death under irradiation by a 160.5 MeV proton beam. The irradiation of MNNG/Hos cells at a dose of 3 Gy in the presence of 80 and 100 ppm of B NPs led to a 2- and 2.7-fold decrease in the number of formed cell colonies compared to control samples irradiated in the absence of NPs. The obtained data unambiguously evidenced the effect of a strong proton therapy enhancement mediated by B NPs. We also found that the proton beam irradiation of B NPs leads to the generation of reactive oxygen species (ROS), which evidences a possible involvement of the non-nuclear mechanism of cancer cell death related to oxidative stress. Offering a series of advantages, including a passive targeting option and the possibility of additional theranostic functionalities based on the intrinsic properties of B NPs (e.g., photothermal therapy or neutron boron capture therapy), the proposed concept promises a major advancement in proton beam-based cancer treatment.

Laser-generated nanoparticles from Fe-based metallic glass in water and its amorphization control by pulsed laser processing

The laser synthesis and processing of colloids represents a group of scalable and “green” synthesis methods of crystalline metal oxides, that have recently made encouraging progresses in preparing amorphous as well as defect-rich nanoparticles. The relevant conditions and mechanisms that allow the design of amorphous metal oxides (AMOs) remain unknown. Consequently, in this work the synthesis of Fe-based partially amorphous oxide nanoparticles (NPs) by pulsed laser ablation in water was studied. Furthermore, both laser pulse duration and the number of laser pulse in pulsed laser fragmentation in liquid (LFL) allow a precise control of amorphization of AMOs in water. Hereby, a high-fluence nanosecond-LFL provides a significantly higher amorphization rate, whereas picosecond-LFL always presents minor fractions of crystalline α-Fe even with a higher specific energy input and laser intensity. Consequently, the laser fluence required for the repeated melting and quenching of NP appears to be the decisive parameter to control amorphization. During laser synthesis and processing of colloids, the amorphization of AMOs appears to be linked to the apparent size reduction effect, while a complete full amorphization of AMOs may be attributed to the stronger oxidation effects. This work will stimulate future studies using laser-generated AMO NPs for further functional purposes.

A single liquid chromatography procedure to concentrate, separate and collect size-selected polyynes produced by pulsed laser ablation in water

Polyynes are linear carbon chains characterized by alternated single and triple bonds and terminated by hydrogen or other terminal substituents. They can be synthesized by pulsed laser ablation in liquid (PLAL) as a scalable, cost-effective, and fast physical technique. Water can be employed as a solvent for PLAL to avoid toxicity problems and to reduce costs compared to organic solvents. However, in in this case, the production yield of polyynes reached is extremely low and prevents further characterization and implementation in new functional materials. In this work, we synthesized polyynes by pulsed laser ablation in water and we optimized the process parameters to improve the yield of polyynes by PLAL. Then, we developed a procedure entirely based on reversed-phase high-performance liquid chromatography (RP-HPLC) which effectively enables the concentration, separation and collection of polyynes according to their length. Since the polyynes sample is an aqueous solution, we could inject it directly into the RP-HPLC column without the dilution step required in the case of a sample in an organic solvent. Thanks to our single RP-HPLC procedure, it is possible to highly increase the concentration and separately characterize different size-selected polyynes for further use in functional materials.

Antibacterial properties of silver nanoparticles synthesized via nanosecond pulsed laser ablation in water

Ag nanoparticles were synthesized in pure water by a nanosecond pulsed laser ablation process and characterized using transmission electron microscopy and ultraviolet-visible spectroscopy. The as-synthesized nanoparticles were determined to have an average particle size of 10.17 ± 2.95 nm. Their absorption spectra were consistent with that of Ag nanoparticles produced through chemical methods. The antibacterial properties of Ag nanoparticles at concentrations of 100 and 250 μg/ml were studied against the gram-positive bacterium Staphylococcus aureus at two infectious inocula (103 and 105 CFU/ml). Over a 24-h test period, the samples containing 100 μg/ml exhibited early bacteriostatic activity but did not stop long-term bacterial growth, while the 250 μg/ml samples demonstrated bactericidal and bacteriostatic effects. These results highlight the use of Ag nanoparticles synthesized through laser ablation as green and effective antibacterial agents for biomedical applications.

Hybrid nanostructures of Ag/Au-ZnO synthesized by pulsed laser ablation/irradiation in liquid

In this study, properties of zinc oxide (ZnO) are tuned by forming hybrid nanomaterials via pulsed laser ablation and irradiation in liquid. Ag/Au bimetallic nanocolloids synthesized by pulsed laser ablation in water are mixed with ZnO powder followed by laser irradiation to form Ag/Au-ZnO nanohybrids. The optical absorption spectra of the hybrid nanomaterials show the presence of plasmonic peaks of Ag/Au. The morphological studies of the nanohybrids reveal the changes in mixed non-uniform morphology to spherical ones. From the structural analysis, the stability of crystalline structure of ZnO is evidenced in all samples, and the high-resolution transmission electron microscopic images showed atomic fringes that correspond to ZnO and Ag/Au. Elemental analysis revealed the compositions from Zn, O, Ag, and Au and their chemical states are confirmed by X-ray photoelectron spectroscopy. Thin films of Ag/Au-ZnO hybrid nanomaterials were fabricated by doctor blade method and annealing effects on morphology, homogeneity of composition and optical properties promoted the visible-light photocatalytic activity. Samples with bimetallic nanoparticles of higher ablation duration showed better photocatalytic performance. Results of this study show the effectiveness of laser ablation and irradiation in liquid technique as a unique green synthesis for obtention of plasmonic hybrid nanomaterials.

Antibacterial activity of Zinc Oxide nanostructured materials synthesis by laser ablation method

Zinc oxide (ZnO) nanostructure (NS) materials with different shapes were synthesis via pulsed laser ablation in water. The characterizations were done using X-ray diffraction XRD, and scanning electron microscopy SEM. The XRD results proved the presence of the (100) and (002) patterns, referring to the ZnO NS. The SEM images show that the structures were changed from flakes with a thickness of about 10-50 nm to spherical like structures with diameter from 24 - 42 nm and high agglomerated. Also, the antibacterial activity of ZnO NS was studied and the results manifested that the inhibition zone in Staphylococcus aureus (S.aureus) is higher than in Escherichia coli (E.coli), which showed an inhibition zone against S. aureus (21mm), as well as against E.coli was (15mm) for ZnO NS prepared at 25 laser pulses, and these activities increased with an increased number of laser pulses for both type of bacteria. Therefore the ZnO NS materials are recommended as a powerful Anti-bacterial material

Synthesis of Ag/Au (core/shell) nanoparticles by laser ablation in liquid and study of their toxicity on blood human components

Q-switch Nd: YAG laser of wavelengths 235nm and 1,460nm with energy in the range 0.2 J to 1J and 1Hz repetition rate was employed to synthesis Ag/Au (core/shell) nanoparticles (NPs) using pulse laser ablation in water. In this synthesis, initially the silver nano-colloid prepared via ablation target, this ablation related to Au target at various energies to creat Ag/Au NPs. Surface Plasmon Resonance (SPR), surface morphology and average particle size identified employing: UV-visible spectrophotometer, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The absorbance spectra of Ag NPs and Ag/Au NPs showed sharp and single peaks around 400nm and 410nm, respectively. The average diameter achieved for Ag/Au NPs were as 30nm and 25nm corresponding to 532nm and 1064nm, respectively. The TEM images showed that Ag/Au NPs possess a spherical shape, while the samples average size were in range from 20 to 30nm. There was an obvious increase in size during the use of 532nm laser. As for the effects of toxicity, results on human blood components showed that these nanoparticles have no effect on RBCs, WBCs and HB Therefore; these particles considered promising in the biological and medical applications.

Synthesis of CdM (M = Se, O) micro and nanoparticles by pulsed laser ablation in water

The pulsed laser is highly used in optics and material sciences, where the high energy of the laser pulse produces an ablation effect that is applied to the obtention of nanoparticles by impacting a target material. We present a complete methodology that includes the preparation of a CdSe target and the synthesis of CdM (M = Se, O) micro and nanoparticles in water by pulsed laser ablation from the previously prepared CdSe target. The laser energy lets to control the properties of particles; we obtain four CdM micro and nanoparticles samples with four different laser energies, that is, 10.25, 20.72, 30.38, and 39.72 mJ. The best result was achieved with 30.38 mJ; at this energy, we obtain nanoparticles with Z‐average size below 100 nm, confirmed by analysis of dynamic light scattering (DLS). In the scanning electron microscopy (SEM) images of the particles obtained at 30.38 mJ, we observed polydispersity in the sample, in addition to irregularly shaped nanoparticles and particle agglomerations. The analysis of the characterization by UV–Vis, energy dispersive spectroscopy (EDS), and X‐ray photoelectron spectroscopy (XPS) suggests the presence of micro and nanoparticles of CdSe and CdO in the sample.

Modification of Cellulose Nanofibers by ZnO Nanoparticles for Gas Sensing

Nanocellulose crystals (NCC) were isolated from the palm fronds by sonication and hydrolyzed processes and modification of them by the prepared ZnO nanoparticles (ZNPs) utilizes pulsed laser ablation in water. NCC:ZNPs layers were fabricated using the spin coating technique. The morphological properties of NCCs and NCC: ZNPs layers were investigated by atomic force microscopy (AFM), scanning electron microscopy and field-effect scanning electron microscope (FESEM) respectively. NCC fibers have been shown a long fibrous shape with layer fibrous sheets about 60 nm of thickness consist of nano tapes between 30 nm to 70 nm of width and thickness sequentially. ZNPs clusters appeared clearly in FE-SEM image as individual growths between 20 nm to 240 nm of size and around NCC fibers. The structural properties of prepared layers have been characterized by X-ray diffraction (XRD) technique, the domain peak of cellulose is found at 22.54° mostly. There is increasing in the crystallinity indices with the number of layers were increased in both NCC and NCC: ZNPs films. The sensing of N2, H2 and NH3 gases were measured, generally the sensitivity of gases increased with adding of ZNPs expect N2.

Nd:YAG纳秒脉冲激光水下烧蚀锗靶研究

Laser ablation in liquid can modify the target morphology, as well as fabricate micro-nano materials in the solution. Many researchers were attracted by this method, because it was chemically clean, low cost and simple operation. Here, germanium particles with micron and submicron scale were prepared by Nd: YAG nanosecond pulsed laser ablation in water. The characteristics of germanium particles were studied by ultraviolet-visible absorption spectrum (uv-vis), X-ray diffraction (XRD) and scanning electron microscope (SEM). Then, studied the target morphology and ablation quality were studued after laser ablation of the germanium target. It was found that the ablation quality increases with the number of laser pulses, but the increase rate decreases, which means the ablation efficiency decreases. Finally, the reasons for the decrease of ablation efficiency were discussed to provide theoretical reference and feasible strategy for improving the preparation rate of materials fabricated by laser ablation in liquid.

Temperature Dependent Up-Conversion Luminescence Properties of Er<sup>3+</sup> Doped KNN Ultrafine Powders Prepared by Pulsed Laser Ablation in Liquid

Er3+ doped potassium sodium niobate (KNN: Er) ultrafine powders have been prepared by pulsed laser ablation in water. X-ray diffraction (XRD) pattern of the sample demonstrated that the as-synthesized powders were crystalized in orthorhombic phase. Scanning electron microscopy (SEM) and transmittance electron microscopy (TEM) images exhibited that the morphology of ultrafine powders are cube-like. Under the excitation of 980 nm laser, the sample exhibits green emission, which is originated from the transition of thermal coupled energy levels (2H11/2, 4S3/2) to ground state level 4I15/2. Temperature dependent up-conversion emission intensity associated with thermal quenching of total green emission band and the fluorescence intensity ratio (FIR) between two sub-emission bands related to population of thermal coupled energy levels are investigated for temperature sensing in the temperature range of 300 K to 480 K. The temperature sensing performances related to different technique were discussed. A maximum relative sensitivity reaches 1.01% K-1 at 464 K for emission intensity thermometry and that is 0.84% K-1 at 374 K for FIR thermometry technique. All these results show that KNN: Er ultrafine phosphors prepared via pulsed laser ablation in water have prospect for non-contact temperature sensing.

Biocompatible nanoparticles production by pulsed laser ablation in liquids

The preparation of spherical metallic nanoparticles (NPs), in the range of 10–100 nm, using pulsed laser ablation in water has particular interest in many scientific fields. The fast released laser energy to the solid metal in water produces plasma at the solid-liquid interface generating NPs in solution. The size distribution and the solution concentration depend by many parameters concerning the laser source (wavelength, pulse energy, pulse duration), the irradiation conditions (target depth in water, focal spot, repetition rate, irradiation time), and the medium where the ablation occurs (water, solution concentration, presence of surfactants). Optimal conditions can be found to control the average particle size, the size distribution, and the coalescence effect. A study of the NPs dependence from the ns pulsed Nd:YAG laser, irradiating metals in water is presented, discussing also the physical characterization of the produced NPs employing microscopy and optical analyses.

Evolution of size distribution of Si nanoparticles produced by pulsed laser ablation in water

In this work, we study ablation of silicon in distilled water under the action of laser pulses with nanosecond duration. The size distribution of produced particles depends on the laser processing parameters and therefore can be modified by the varying distance between laser pulses, laser fluence or pulse duration. The properties of fabricated nanostructures are investigated by scanning electron microscopy to acquire statistical information on nanoparticle sizes. These results can be promising for dielectric nanophotonics, photovoltaics or cancer treatment where relatively large spherical silicon particles are necessary.

Preparation and characterization of carbon nanotubes by pulsed laser ablation in water for optoelectronic application

Abstract In the present work, preparation of multi-walled carbon nanotubes (MWCNTs) and carbon nanoparticles (CNPs) by using pulsed laser ablation of a graphite target in water without using catalyst was demonstrated. The effect of laser wavelength on the optical absorption and structural properties has been studied. X-ray diffraction (XRD) data shows the synthesized CNTs were polycrystalline and a peak related to the diamond structure was observed. Scanning electron microscope (SEM) investigation displays that the average diameter of CNTs synthesized with 532 nm was 20 nm and few micrometers in length, while the CNTs synthesized with 1064 nm have an average diameter of 75 nm and lengths of few sub-micrometers. Some of CNPs were noticed to deposit on the CNTs. Transmission electron microscope (TEM) was used to study the morphology of MWCNTs. Raman spectra confirm formation of MWCNTs during the presence of three peaks belonged to D-band, G-band and 2D-band. The intensity ratio of IG/ID is larger than unity for MWCTs prepared by two laser wavelengths. The colloidal MWCNTs prepared by 532 nm laser pulses showed higher absorption than that of MWCNTs prepared with 1064 nm. The current-voltage characteristics and responsivity of hybrid In/p-MWCNTs/n-Si heterojunction photodetectors prepared at different CNTs film thicknesses were investigated at room temperature. The responsivity of hybrid MWCNTs/n-Si photodetector has two peaks of response, the first peak was found at 650 nm and the second peak located at 850 nm. The maximum responsivity was 0.53 A/W at 532 nm was found for the photodetector fabricated with 532 nm laser. The energy band diagram of MWCNTs/Si heterojunction was constructed under illumination condition.

Synthesis of bismuth nanoparticles for biomedical applications

Bismuth is a biocompatible material that can be employed in the form of nanoparticles to be used as a possible alternative contrast medium for diagnostics. In particular, it has been prepared as spherical nanoparticles in liquid solution by using the technique of the pulsed laser ablation in water. The high atomic number Bi nanoparticles in the solution show surface plasmon resonance effects, high mass absorption coefficient for soft X-ray interaction and high electron and nuclear stopping powers for electrons and ion beams. This biocompatible solution can be injected into living systems, such as mice, in order to study the up-take effect in different organs with a high contrast spatial localization of the X-ray images in the tissues in which the nanoparticles are confined. The high contrast medium for high-resolution imaging in biological systems can be also used as targeting for successive exposure to ionizing radiation during radiotherapy or hyperthermia of diseased cells. The obtained results demonstrate high contrast images of Bi nanoparticles in biological environment by using the X-ray fluorescence in the electron microscopy and the X-ray absorption in mice.

Aspects of the Formation of Tin Oxide under Annealing of Nanopowders Obtained by Pulsed Laser Ablation of Metallic Tin in Aqueous Media

Nanocolloids, obtained by pulsed laser ablation (Nd:YAG laser, 1064 nm, 7 ns, 150 mJ) of metallic Sn in distilled water and also in solutions of hydrogen peroxide and nitric acid, were dried and subjected to heat treatment at different temperatures up to 800°С. It has been shown that addition of H2O2 or HNO3 has an effect not only on the size characteristics and structure of the initial nanoparticles, but also on the process of formation and the final characteristics of SnO2 under annealing. By the method of powder x-ray diffraction it was established that in the case of pulsed laser ablation in water and in a solution of nitric acid, the initial particles contain the phase SnO, but for annealed sample obtained by ablation in HNO3, an intermediate orthorhombic phase of SnO2 is formed. Additional studies using Raman spectroscopy and thermal analysis made it possible to determine the presence of tin hydroxide in the initial samples and formation of intermediate forms of its oxides, SnOx, upon annealing.