- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Handbook of Nanoparticles || Laser Fabrication of Nanoparticles
摘要： Lasers are widely used for material processing (cutting, drilling, cleaning, ?lm deposition, etc.). A recent application is for nanoparticle fabrication. Pulsed laser ablation is by far the fastest and clean method to fabricate nanoparticles directly from bulk targets. For this purpose, target ablation is performed in vacuum, in gas atmosphere, or in liquids with fast (nanosecond) and ultrafast (picosecond, femtosecond) laser pulses. Mostly metal but also semiconductor and ceramic nanoparticles were fabricated. In the early stage of this technique, the main problem was the large size distribution of the produced nanoparticles. But the possibility to independently handle laser pulse characteristics (wavelength, power density, pulse duration, etc.) and the accurate control and optimization of the ambient parameters is leading to an ef?cient tailoring of the nanoparticle size, due also to helpful theoretical and numerical models. A review is presented of the most important studies and of the obtained results.
关键词： laser ablation in liquids,ps-laser ablation,oxide nanoparticles,fs-laser ablation,metal nanoparticles,semiconductor nanoparticles,ns-laser ablation
更新于2025-09-23 15:19:57
-
Optical control of layered nanomaterial generation by pulsed-laser ablation in liquids
摘要： Pulsed-laser ablation in liquids capitalizes on combining chemical and optical control to rapidly generate size, composition, and phase-controlled nanostructures, without the need for surfactants. Very high temperatures, which we determined to be ca. (8,400 ± 1,300) K, pressures, and ion densities exist in the laser-induced liquid-confined plasma. These unique conditions, coupled with the rapid cooling during which nanoparticles are formed, permitted access to new extreme regions of materials’ phase diagrams. This way, we produced metastable layered copper and zinc hydroxide-based nanocrystals with interesting physical properties that can serve as precursors for two-dimensional inorganic semiconductor nanomaterials.
关键词： LTE spectra,optical control,electron temperature,layered nanocrystals,Pulsed-laser ablation in liquids,laser-induced plasma
更新于2025-09-23 15:19:57
-
Study of the physicochemical surface alterations and incubation phenomena induced on iron targets by nanosecond pulsed laser ablation in liquids: Effect on productivity and characteristics of the synthesized nanoscale zero-valent iron (nZVI) particles
摘要： This work presents a systematic study of the significant role of the surface physicochemical alterations produced during the laser ablation of massive iron disks submerged in different solvents on the generation of colloidal iron nanoparticles. For that purpose, the laser ablation thresholds and the incubation coefficients for various pulse numbers per site and pulse energies have been measured under distilled water (DW) and ethanol (EtOH). After that, a complete physicochemical characterization of these targets indicated higher threshold fluence values for the ablation experiments conducted in EtOH than those performed in DW. The threshold fluence values decreased also with the decrease of the pulse overlap for both solvents, being it much more pronounced in EtOH. In addition, the related incubation coefficient showed that the incubation effect is lower for experiments conducted in DW. The characteristics of the synthesized nZVI particles were also a function of the solvent nature and the pulse overlap: laser ablation in DW leaded to iron oxide nanoparticles, whereas core-shell iron nanoparticles were obtained in EtOH. Moreover, high pulse overlap values lead to chemical alterations, resulting in a decrease of the composition homogeneity and a strong increase of the nanoparticle polydispersity.
关键词： Incubation effect,Nanosecond pulsed laser ablation in liquids,Raman spectroscopy,Colloidal nanoscale zero-valent iron particles,Laser ablation threshold,Laser induced-chemical surface alteration
更新于2025-09-19 17:13:59
-
Effect of liquid environment on single-pulse generation of laser induced periodic surface structures and nanoparticles
摘要： The effect of a liquid environment on the fundamental mechanisms of surface nanostructuring and generation of nanoparticles by single pulse laser ablation is investigated in a closely integrated computational and experimental study. A large-scale molecular dynamics simulation of spatially-modulated ablation of Cr in water reveals a complex picture of dynamic interaction between the ablation plume and water, which involves rapid deceleration of the ablation plume by water environment, formation and prompt disintegration of a hot metal layer at the interface between the ablation plume and water, lateral redistribution and redeposition of a major fraction of the ablation plume, and eventual formation of smooth frozen surface features. A good agreement between the shapes of the surface features predicted in the simulation and the ones generated in single pulse laser ablation experiments performed for Cr in water supports the mechanistic insights revealed in the simulations. The results of this study suggest that the presence of liquid environment can eliminate the sharp features of surface morphology, reduce the amount of material removed from the target by more than an order of magnitude, and narrow down the nanoparticle size distribution as compared to laser ablation in vacuum. Moreover, the computational predictions of the effective incorporation of molecules constituting the liquid environment into the surface region of the irradiated target and the generation of high vacancy concentrations exceeding the equilibrium levels by more than an order of magnitude suggest a potential for hyperdoping of laser-generated surfaces by solutes present in the liquid environment.
关键词： Laser-Induced Periodic Surface Structures (LIPSS),Generation of Nanoparticles,Crystal Defects,Surface Morphology,Hyperdoping,Molecular Dynamics Simulations,Pulsed Laser Ablation in Liquids
更新于2025-09-19 17:13:59
-
Synthesis of silicon nanoparticles by laser ablation at low fluences in water and ethanol
摘要： Colloidal silicon nanoparticles (Si-nc) where synthesized by laser ablation of a solid Si target in water and ethanol. The target was immersed in a vessel containing the solvent and irradiated during 5 and 10 min at different ?uences: 0.530, 0.608, 0.687 J cm?2. Ablation was carried out using a laser wavelength of 1064 nm. The obtained colloidal nanoparticles were irradiated after the synthesis to evaluate if laser fragmentation could be produced. In addition, a series of nanoparticles using ethanol as liquid medium was synthesized ablating with 532 nm. Colloidal nanoparticles were structurally characterized by Raman spectroscopy and Transmission Electron Microscopy. Size of the Si-nc were calculated by the theorical models: Bond Polarizability Model (BPM) and One-Phonon Con?nement Model (PCM), where nanocrystals ranging from 2 to 11 nm were found.
关键词： Si nanoparticles,laser fragmentation,laser ablation in liquids
更新于2025-09-19 17:13:59
-
ZnO colloids and ZnO nanoparticles synthesized by pulsed laser ablation of zinc powders in water
摘要： ZnO nanoparticles (NPs) were synthesized by pulsed laser ablation of zinc powders suspending in deionized water. The synthesized ZnO NPs were characterized for morphology, structure and optical properties. The ZnO NPs have irregular shapes sized in 10–50 nm and possess a wurtzite structure with polycrystallinity in nature, and grew without a preferential orientation. The supernatant solutions obtained by laser ablation of zinc powders in water exhibit the typical optical absorption edge of wurtzite ZnO near 380 nm and emit a photoluminescence composed of a narrow ultraviolet peak and a broad visible band, characteristics of the near-band-edge emission and the deep-level defects related emission of ZnO, respectively. The formation of ZnO NPs was further confirmed by structural and optical characterization performed for the aggregated ZnO NPs obtained by drop-casting the ZnO colloidal solutions onto Si wafers. And the effects of annealing in N2 on the structure and photoluminescence of the ZnO NPs transferred on Si were also examined.
关键词： ZnO,Laser ablation in liquids,Nanoparticles,Colloids,Deep-level defects
更新于2025-09-19 17:13:59
-
The effect of pulse duration on nanoparticle generation in pulsed laser ablation in liquids: Insights from large-scale atomistic simulations
摘要： The generation of colloidal solutions of chemically clean nanoparticles through pulsed laser ablation in liquids (PLAL) has evolved into a thriving research field that impacts industrial applications. The complexity and multiscale nature of PLAL make it difficult to untangle the various processes involved in the generation of nanoparticles and establish the dependence of nanoparticle yield and size distribution on the irradiation parameters. Large-scale atomistic simulations have yielded important insights into the fundamental mechanisms of ultrashort (femtoseconds to tens of picoseconds) PLAL and provided a plausible explanation of the origin of the experimentally observed bimodal nanoparticle size distributions. In this paper, we extend the atomistic simulations to short (hundreds of picoseconds to nanoseconds) laser pulses and focus our attention on the effect of the pulse duration on the mechanisms responsible for the generation of nanoparticles at the initial dynamic stage of laser ablation. Three distinct nanoparticle generation mechanisms operating at different stages of the ablation process and in different parts of the emerging cavitation bubble are identified in the simulations. These mechanisms are (1) the formation of a thin transient metal layer at the interface between the ablation plume and water environment followed by its decomposition into large molten nanoparticles, (2) nucleation, growth, and rapid cooling/solidification of small nanoparticles at the very front of the emerging cavitation bubble, above the transient interfacial metal layer, and (3) spinodal decomposition of a part of the ablation plume located below the transient interfacial layer, leading to the formation of a large population of nanoparticles growing in a high-temperature environment through inter-particle collisions and coalescence. The coexistence of the three distinct mechanisms of the nanoparticle formation at the initial stage of the ablation process can be related to the broad nanoparticle size distributions commonly observed in nanosecond PLAL experiments. The strong dependence of the nanoparticle cooling and solidification rates on the location within the low-density metal-water mixing region has important implications for the long-term evolution of the nanoparticle size distribution, as well as for the ability to quench the nanoparticle growth or dope them by adding surface-active agents or doping elements to the liquid environment.
关键词： phase explosion,pulsed laser ablation in liquids,molecular dynamics simulations,hydrodynamic instability,atomistic simulations,nanoparticles,nucleation and growth
更新于2025-09-19 17:13:59
-
Investigating double pulse nanoparticle enhanced laser induced breakdown spectroscopy
摘要： Several strategies have been e?ectively tested in the past to improve the Laser Induced Breakdown Spectroscopy (LIBS) signal, involving peculiar experimental con?gurations, such as Double Pulse LIBS (DP-LIBS). Recently, sample treatment has proven to be a viable and simple way to enhance the LIBS performances; in particular, the Nanoparticle-Enhanced LIBS (NELIBS) methodology uses a deposition of metal nanoparticles (NPs) on the sample to greatly increase the emission of the LIBS plasma. In this work, we investigate the possibility of combining, for the ?rst time, DP-LIBS with NELIBS. The chosen set-up uses two parallel non-collinear laser pulses to ensure the activation of NPs during both pulses, while maintaining the low-pressure environment typical of DP-LIBS. The two laser beams are spatially separated so that the second beam is focused within the shock wave generated by the ?rst one. This con?guration allows the exploitation of the combined enhancement of both DP-LIBS and NELIBS. Several tests on copper targets have been performed to determine the best set-up for the maximum magnitude of the signal enhancement by adjusting di?erent parameters such as pulse energies and o?set distances. Commercially available silver NPs and NPs prepared by pulsed laser ablation in liquid have been tested and their performances compared with standard DP-LIBS.
关键词： Pulsed laser ablation in liquids,Double pulse LIBS,Nanoparticle enhanced LIBS,Spatially o?set DP-NELIBS,Signal enhancement
更新于2025-09-19 17:13:59
-
Structural and optical properties of nanoparticles formed by laser ablation of porous silicon in liquids: Perspectives in biophotonics
摘要： The paper discusses the possibility of manufacturing silicon nanoparticles, which are suitable for contrasting biological tissues imaged by optical coherence tomography, by femtosecond laser ablation of porous silicon in various liquids. The manufactured nanoparticles are characterised by average sizes of 87, 112, and 102 nm for cases of ablation in water, ethanol, and liquid nitrogen, respectively, as well as a relatively narrow size distribution, which provides additional advantages for subsequent delivery into biological tissues. Electro chemical etching, which results in the formation of layers of porous silicon, allows the yield of ablation products to be increased several-fold by lowering the ablation threshold, thereby increasing the light scattering efficiency of the prepared suspensions compared with the case of using crystalline silicon as targets. The possibility of obtaining high-contrast images of a biotissue phantom based on an agar gel with embedded nanoparticles is shown. The magnitude of the contrast depends on the liquid used for ablation and correlates with the values of the reduced scattering coefficient of the studied suspensions.
关键词： silicon nanoparticles,laser ablation in liquids,atomic force microscopy,light scattering,optical coherence tomography,spectrophotometry
更新于2025-09-19 17:13:59
-
Numerical Investigation of Ultrashort Laser-Ablative Synthesis of Metal Nanoparticles in Liquids Using the Atomistic-Continuum Model
摘要： We present a framework based on the atomistic continuum model, combining the Molecular Dynamics (MD) and Two Temperature Model (TTM) approaches, to characterize the growth of metal nanoparticles (NPs) under ultrashort laser ablation from a solid target in water ambient. The model is capable of addressing the kinetics of fast non-equilibrium laser-induced phase transition processes at atomic resolution, while in continuum it accounts for the effect of free carriers, playing a determinant role during short laser pulse interaction processes with metals. The results of our simulations clarify possible mechanisms, which can be responsible for the observed experimental data, including the presence of two populations of NPs, having a small (5–15 nm) and larger (tens of nm) mean size. The formed NPs are of importance for a variety of applications in energy, catalysis and healthcare.
关键词： metal nanoparticles,femtosecond laser ablation,dual nanoparticle distribution,pulsed laser ablation in liquids
更新于2025-09-16 10:30:52