D121 液相レーザーアブレーションによるZnOナノ粒子の生成(プラズマ利用技術の進展II)

We report the preparation of silicon nanocrystals with efficient ultraviolet luminescence by nanosecond pulsed laser ablation in de-ionized water at a high laser fluence condition. Atomic force microscopy results show that nano-grains form in the process of laser ablation. Fourier transform infrared spectroscopy analyses indicate that silicon nanocrystals are formed and partially oxidized during synthesis. The photoluminescence measurement and the ultraviolet-visible transmittance spectroscopy of the samples prepared at various fluences reveal that all the prepared samples present an efficient ultraviolet emission at room temperature and it can be attributed to the quantum confinement effect and surface defect states. The emission wavelength of silicon nanocrystals is far shorter than visible light, which means potential applications in optoelectronic devices.

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

Pulsed Laser Ablation in liquid (PLAL) is considered as a robust and simple technique for producing nanoparticles (NPs) using lasers. The carbon-based nanoparticles were fabricated via the PLAL approach by irradiating a graphite target with a pulsed Nd:YAG laser of wavelength 532 nm. The graphite target was immersed in distilled water and irradiated for 10 min. The pulse length, reputation rate, and fluence were 6 ns, 10 Hz, and 0.4 J cm−2, respectively. The structural and physical properties of the synthesized NPs were investigated and analyzed using different characterization methods. For example, Transmission Electron Microscopy (TEM) images revealed diverse carbon nanostructures such as graphene nanosheets, nanospheres, nanospheres in the shape of a necklace, and nanotubes. The spectrum of Energy Dispersive X-Ray spectroscopy (EDX) confirmed successful synthesis of high purity carbon nanostructures. Moreover, the result of X-Ray Diffraction (XRD) Spectroscopy indicated the presence of reduced Graphene Oxide (rGO) with a (002) plane and the absence of Graphene Oxide (GO). The transmission spectrum from Ultraviolet-Visible (UV–vis) analysis showed a strong trough at 266 nm which is attributed to the presence of carbon nanostructures. Furthermore, Fourier-Transform Infrared Spectroscopy (FTIR) analysis demonstrated the vibration bonds related to carbon. The nanostructures produced were semi-stable with little agglomeration as was inferred from the results of the Zeta Potential. Finally, the Dynamic Light Scattering (DLS) analysis supported the TEM results. PLAL technique is proved to be a simple method for producing carbon-based nanomaterials. Moreover, the laser fluence was found to be an important factor which affects greatly the type of nanostructures that could be synthesized during laser ablation.

Views Icon Views Article contents Figures & tables Video Audio Supplementary Data Peer Review Share Icon Share Twitter Facebook Reddit LinkedIn Tools Icon Tools Reprints and Permissions Cite Icon Cite Search Site Citation Siti Masyithah, Muhammad Hilmy Alfaruqi, Nurfina Yudasari, Muhandis Shiddiq; Fabrications of ZnO and Zn nanoparticles by pulsed laser ablation in water and acetone. AIP Conf. Proc. 28 February 2024; 3003 (1): 020122. https://doi.org/10.1063/5.0186540 Download citation file: Ris (Zotero) Reference Manager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentAIP Publishing PortfolioAIP Conference Proceedings Search Advanced Search |Citation Search

The rutile-type TiO2 powders originally whitish and micrometer in size were successfully reduced in size with accompanied structure, composition and optical property change to become dark bluish by pulsed laser ablation in liquid under 532 nm excitation and 400 mJ per pulse at a specified water depth (5 or 15 mm) for up to 30 min. Transmission electron microscopic observations indicated the newly formed anatase nanoparticles are ca. 5 nm in size with spindle-like shape having well-developed {101} faces and -(001) facets for mutual coalescence into unity. The -(001)-specific coalescence twin of anatase was also observed. There are also amorphous nanoparticles in association with anatase, minor brookite and relic rutile with 2 x (110) superstructure. The resultant colloidal TiO2 nanoparticles are (Ti3+, Ti2+, H+) co-signified according to optical spectroscopic results and have a bimodal minimum band gaps 3.12 and 2.66 eV due to nanocrystals and amorphous phase, respectively, for potential optocatalytic applications in UV-visible range.

In this work we study the effect of extra laser irradiation during the preparation by pulsed laser ablation in water on the structure and physicochemical properties of titanium dioxide. Extra laser irradiation leads to a decrease in particle size, a change in structure, and as a result, a change in optical and photocatalytic properties.

Pulsed laser ablation (PLA) is a unique method used to obtainatoms, ions, and small molecules from solid targets because ofits high-energy output, the ability to adjust the power of thelaser, and the purity of the final product.1,2 Most experiments onpulsed laser-solid interaction have been carried out in vacuum(10−4 Pa)3 or in a low pressure background gas,4 aiming at thin film fabrication and cluster formation.1 One of the advantages ofthe PLA method is that stoichiometric thin films can be preparedwith the same composition as the target materials. In addition,metals, semiconductors, and ceramics with high melting point canbe obtained at lower temperatures. However, this method has somedisadvantages, such as the size of the granules on the surface ofthin films is not even, big particles exist in the surface, and ahigh vacuum environment raises the preparation cost. Also, it isdifficult to obtain a thin film with big area using the PLA method.Some researchers have attempted to produce new materials by PLAin a static liquid medium. Figure 11.1 shows a typical schematicdiagram of the experimental apparatus of PLA in static liquid.5Mafune´ and coworkers prepared small silver, gold, and platinumclusters by laser ablation of ametal plate in the aqueous solution of asurfactant, where the clusters are encapsulated by the surfactant. Atthe same time, they also researched the influence of the preparationconditions, such as the concentration of the surfactant and thepower of laser ablation, on the stability of the nanoparticles in thesolution.5−8 Yang and coworkers prepared nanocrystalline diamond and cubic C3N4 by laser ablation of a graphite target in acetonesolution and ammonia solution, respectively.9,10,11 Iwabuchi et al.12prepared nanosized titania particles by PLA of a rutile single-crystaltarget in water. Compagnini et al.13 reported PLA of gold andsilver in several liquids (mainly water, ethanol, and chloroform).They observed the formation of metal sols by laser ablation inwater and ethanol and the formation of chloride compound solsby laser ablation in chloroform. This revealed that the chemicalstate of the formed nanoparticles depends mainly on the chemicalreactivity of the liquid. Liang et al.14 synthesized ultrafine SnO2−x nanocrystals by PLA of a tin metal plate in aqueous solutions ofsodium dodecyl sulfate and in pure water. Yeh and coworkers15also prepared aluminum hydroxides by laser ablation of an Al rodimmersed in water solvent. During aging, bayerite, gibbsite, andboehmite particles were formed simultaneously.

The emission of silicon nanocrystals (Si-NCs), synthesized by pulsed laser ablation in water, was investigated on varying the pH of the solution. These samples emit μs decaying orange photoluminescence (PL) associated with radiative recombination of quantum-confined excitons. Time-resolved spectra reveal that both the PL intensity and the lifetime increase by a factor of ∼20 when the pH decreases from 10 to 1 thus indicating that the emission quantum efficiency increases by inhibiting nonradiative decay rates. Infrared (IR) absorption and electron paramagnetic resonance (EPR) experiments allow addressing the origin of defects on which the excitons nonradiatively recombine. The linear correlation between the PL and the growth of SiH groups demonstrates that H+ ions passivate the nonradiative defects that are located in the interlayer between the Si-NC core and the amorphous SiO2 shell.

Palladium nanoparticles produced by CW and pulsed laser ablation in water

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.

Effect of aging on copper nanoparticles synthesized by pulsed laser ablation of copper plate in water was studied. By characterization studies of the aged nanoparticles, it is found that copper nanoparticles converted into Cu@Cu2O nanostructure. The synthesized nanomaterial is characterized with UV-Visible absorption, transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infrared (FTIR) and Raman and photoluminescence (PL) spectroscopic techniques. TEM image shows that the aged nanoparticles get assembled into cactus like structure and are spherical in shape with average diameter 7 nm and dispersion 2 nm. XRD and FTIR spectrum confirm the formation of Cu@Cu2O in the aged sample. Raman spectrum also confirms the presence of Cu2O nanoparticles. PL spectrum of the aged nanoparticles shows a direct allowed transition with bandgap energy of 2·24 eV. The mechanism for synthesis of core-shell nanoparticles and formation of self-assembly of nanoparticles is also discussed.

Magnetite (Fe3O4) nanoparticles of 1–10 nm (with the maximum at 2 nm) were obtained via pulsed laser ablation of iron target in water in form of a stable dispersion without addition of surfactants and stabilizers. The structure of the material obtained was investigated using transmission electron microscopy, scanning electron microscopy, and Brunauer–Emmett–Teller methods. To investigate the composition of the particles in the sample, such methods as Fourier transform infrared spectroscopy, Raman spectroscopy, differential scanning calorimetry, and X-ray diffraction, were applied. Magnetite phase was found to be sufficiently pure, it was not contaminated by other iron oxide phases and contained not more than 0.5% of metallic iron in form of large particles. The study of the magnetic properties of the magnetite nanoparticles obtained has shown that they exhibit ferrimagnetic behavior at room temperature with the paramagnetic contribution explained by the presence of fine superparamagnetic particles.

Zinc oxide (ZnO) and copper oxide (CuO) nanoparticles were created using Nd-YAG pulse ablation, and they were subsequently examinedas colloidal solutions. The produced nanoparticles were examined for UV-VIS absorption using transmission electron microscopy (TEM) andFourier transform infrared spectroscopy (FTIR) (TEM). The production of zinc oxide and copper oxide nanoparticles is shown by FTIRcharacterization. the subsequent tests for UV-VIS absorption. According to TEM, the nanoparticle sizes varied from (30) nm for zinc oxide to(40) nm for copper oxide. X-ray diffraction was used to describe the films' structure (XRD)The X-ray showed the monoclinic crystallinestructure of CuO and the hexagonal wurtzite phase of ZnO. Due to their antibacterial properties, copper oxide nanoparticles with a size rangeof 54.35–40.16 nm and zinc oxide nanoparticles with a size range of 36.16 nm were found to display FESM.

Processes involved in the synthesis of metal oxide nanoparticles by means of milli-second pulsed laser ablation in water

In this paper, we propose a simple two-step method for the synthesis of Ag, Au, and Pt-doped ZnO nanoparticles. The method is based on the fabrication of targets using the pulsed laser deposition (PLD) technique where thin layers of metals (Ag, Pt, Au) have been deposited on a metal-oxide bulk substrate (ZnO). Such formed structures were used as a target for the production of doped nanoparticles (ZnO: Ag, ZnO: Au, and ZnO: Pt) by laser ablation in water. The influence of Ag, Au, and Pt doping on the optical properties, structure and composition, sizing, and morphology was studied using UV-Visible (UV-Vis) and photoluminescence (PL) spectroscopies, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and transmission electron microscopy (TEM), respectively. The band-gap energy decreased to 3.06, 3.08, and 3.15 for silver, gold, and platinum-doped ZnO compared to the pure ZnO (3.2 eV). PL spectra showed a decrease in the recombination rate of the electrons and holes in the case of doped ZnO. SEM, TEM, and AFM images showed spherical-shaped nanoparticles with a relatively smooth surface. The XRD patterns confirm that Ag, Au, and Pt were well incorporated inside the ZnO lattice and maintained a hexagonal wurtzite structure. This work could provide a new way for synthesizing various doped materials.