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As nanomaterials find applications in an increasingly diverse range of fields such as wastewater treatment, biotechnology and flexible electronics, the demand for nanomaterials with specific proper...

Nonequilibrium nanoalloys are metastable solids obtained at the nanoscale under nonequilibrium conditions that allow the study of kinetically frozen atoms and the discovery of new physical and chemical properties. However, the stabilization of metastable phases in the nanometric size regime is challenging and the synthetic route should be easy and sustainable, for the nonequilibrium nanoalloys to be practically available. Here we report on the one-step laser ablation synthesis in solution (LASiS) of nonequilibrium Au-Co alloy nanoparticles (NPs) and their characterization on ensembles and at the single nanoparticle level. The NPs are obtained as a polycrystalline solid solution stable in air and water, although surface cobalt atoms undergo oxidation to Co(II). Since gold is a renowned plasmonic material and metallic cobalt is ferromagnetic at room temperature, these properties are both found in the NPs. Besides, surface conjugation with thiolated molecules is possible and it was exploited to obtain colloidally stable solutions in water. Taking advantage of these features, an array of magnetic-plasmonic dots was obtained and used for surface-enhanced Raman scattering experiments. Overall, this study confirms that LASiS is an effective method for the formation of kinetically stable nonequilibrium nanoalloys and shows that Au-Co alloy NPs are appealing magnetically responsive plasmonic building blocks for several nanotechnological applications.

Currently, most of the red colored glasses are still produced using cadmium sulfoselenide, despite its high toxicity. Alternative solutions, more environmentally friendly, have been sought, most of them going through the use of gold or copper nanoparticle, the color being obtained by striking. This work presents a new methodology for production of a red colored glass by the incorporation of gold nanoparticles in the melt, trying to take advantage of an amorphous silica layer involving the nanoparticles. Gold nanoparticles (AuNP) were produced by laser ablation synthesis in solution (LASiS), using a solution of tetraethyl orthosilicate (TEOS) and isopropanol (IPA). A xerogel was prepared using the TEOS:IPA:AuNp suspension, mixed with a alkaline-earth aluminosilicate colorless glass and melted at 1350 °C producing a glass with an intense and homogeneous ruby red color without the need of a striking stage.

As nanomaterials find applications in an increasingly diverse range of fields such as wastewater treatment, biotechnology and flexible electronics, the demand for nanomaterials with specific properties has increased. This increase is coupled with an increasing emphasis on nanomaterials with highly specific properties for specialised applications. Industrially, nanomaterials are produced via wet- chemical techniques which employ the use of solvents and reagents which are environmentally harmful. As we move forward with the use of nanomaterials, the ability to produce nanomaterials in a sustainable manner has become a topic of great significance. Towards this end, Laser Ablation Synthesis in Solution (LASiS) is a physical production technique capable of producing tailored nanomaterial colloids in a sustainable manner. These colloids are produced by ablating a solid target immersed in a solvent using a laser. Typically, LASiS is conducted in a batch process and in small volumes limiting commercial viability. To overcome this, there has been a move towards the use of continuous production via LASiS using flow systems. This allows an increase in nanomaterial yield, resulting in colloid concentrations approaching those of commer- cial colloids. This work investigates a new production technique incorporating a laminar recirculatory flow system to produce stable high concentration nano-silver colloids.

Driven by an ever-increasing demand for nanomaterials with specific functionalities, physical synthesis techniques such as Laser Ablation Synthesis in Solution (LASiS) have gained significant interest over in recent years. Commercial wet chemical synthesis methods, while having significantly higher nanomaterial yields than LASiS, typically have considerable negative environmental impact through the use of harmful reagents and solvents. LASiS therefore represents a route towards the sustainable “green” production of nanomaterials however the significant challenge to its commercialization is that of comparably low nanomaterial yields. Significant effort has been made towards increasing the production rates of LASiS, however many of the reported advances have relied on the use of high power (>20 W) or short pulse (

In the recent past, gold nanoparticles synthesized using pulsed laser ablation in biocompatible mediums has attracted scientific and technological interest. In this work, it is found that the gold nanoparticles prepared using laser ablation of gold target in water is inherently non-toxic. These particles have shown that they are photothermally active when excited with 532 nm laser line, in conjunction with the plasmon band. The surface charge of these nanoparticles is found to be negative. The X-ray photoelectron spectroscopy measurements indicated the possibility of partial oxidation of the surfaces of these gold nanoparticles and electron micrographs indicated that the surfaces of these particles are relatively smooth. Raman measurements made with crystal violet as probe molecules using these nanoparticles as substrates and Raman spectra from L929 cells after incubation with these gold nanoparticles have shown that they can enhance the scattered Raman signal.

In this paper, we demonstrate two-dimensional nanohole array substrates prepared using the visible laser ablation technique. We fabricated Au/polymer hybrid thin films where the Au nanoparticles were fixed onto the block copolymer substrate, which was used as the microphase-separated structure. The film was coated with a thin layer of poly(methyl acrylate), and was then irradiated with a nanosecond 532 nm pulsed laser light. The light excited the resonant plasmon absorption band of the Au nanoparticles. The nanoparticles underwent explosive vaporization via a superheated state, resulting in the formation of two-dimensional nanohole arrays on the film surface. The relevant mechanism aspects of the nanohole formation process and the relationship with laser fluence are presented.

In this paper, we investigate experimentally the effect of electric field on the size, optical properties and crystal structure of colloidal nanoparticles (NPs) of aluminum prepared by nanosecond Pulsed Laser Ablation (PLA) in deionized water. The experiments were conducted for two different conditions, with and without the electric field parallel to the laser beam path and the results were compared. To study the influence of electric field, two polished parallel aluminum metals plates perpendicular to laser beam path were used as the electrodes. The NPs were synthesized for target in negative, positive and neutral polarities. The colloidal nanoparticles were characterized using the scanning electron microscopy (SEM), UV–vis absorption spectroscopy and X-ray Diffraction (XRD). The results indicate that initial charge on the target has strong effect on the size properties and concentration of the synthesized nanoparticles. The XRD patterns show that the structure of produced NPs with and without presence of electric field is Boehmite (AlOOH).

Preparation of doped ZnO nanoparticles (NPs) represents a challenging task due to the tendency of self-compensation of the introduced defects by the intrinsic ones. One of the possible ways of achieving reliable p-doping in ZnO is dual acceptor doping, i.e. simultaneous introduction of two types of acceptors. In the present paper the capabilities of laser ablation and post-irradiation processes for preparation of N-doped and Ag-, N-co-doped ZnO NPs were investigated. In order to obtain doped ZnO NPs, Nd:YAG laser ablation of Zn in ammonium nitrate (NH4NO3) solution and sequential laser ablation of Ag and Zn in ammonium nitrate solution were used. The composition, structure and morphology of the prepared NPs were controlled through an additional treatment of the colloids by the second harmonic of the Nd:YAG laser. The influence of the ablation processes sequence and additional laser irradiation parameters on the morphology, structural, optical characteristics and chemical composition of the synthesized NPs was examined. The results obtained reveal that the doping takes place after laser ablation of zinc in ammonium nitrate and silver target in the ZnO colloid in NH4NO3 solution that was confirmed by X-ray photoelectron spectroscopy analysis indicating the substitution of N at O site.

The synthesis processes of metallic nanoparticles have seen a growing interest in recent years, mainly by the potential applications of the phenomenon of localized surface plasmon resonance associated with metallic nanoparticles. This paper shows a fast method to synthesize silver, gold and silver/gold alloy nanoparticles coated with a porous silica shell by the assisted laser ablation method in three steps. The method involves a redox chemical reaction where the reducing agent is supplied in nanometric form by laser ablation. In the first step, a silicon target immersed in water is ablated for several minutes. Later, AgNO3 and HAuCl4 aliquots are added to the solution. The redox reaction between the silver and gold ions and products resulting from ablation process can produce silver, gold or silver/gold alloy nanoparticles coated with a porous silica shell. The influence of the laser pulse energy, ablation time, Ag+ and Au3+ concentration, as well as the Ag+/Au3+ ratio, on optical and structural properties of the nanostructures was investigated. This work represents a step forward in the study of reaction mechanisms that take place during the synthesis of nanoscale materials by the assisted laser ablation technique.

Extended colloidal stability and high dispersion degree of nanolubricants are required to avoid nanoparticle deposition in combustion engines and to reduce friction and wear. In this study, the simple and rapid one-step technique of pulsed laser ablation in liquids is employed to synthesize precursor-free and highly-dispersed gold nanoparticles while the colloidal stability is measured by optical spectroscopy and transmission electron microscopy. We determine a remarkable colloidal stability at engine-like (2 h circulation, 150 °C, 6 bar) and ambient conditions for 9 months in terms of constant primary particle size. In contrast to additive-free oils, almost no agglomeration is observed, which might be attributed to the attachment of engine oil additives or pyrolyzed/oxidized molecules to the nanoparticles preventing attractive nanoparticle interactions.

Laser ablation of Zn target in water, ammonium nitrate and cetyltrimethyl ammonium bromide (CTAB) was carried out to synthesize spherical, nanoflakes, nanosquares, nanoflowers and branched nanorods ZnO structures. Morphology of the ZnO nanostructures is controlled by varying ambient condition around laser generated plasma by means of either liquid temperature or addition of surfactant CTAB. In situ heating at temperature to 45, 65 and 85 C resulted in morphology variation from spherical to nanoflakes while ex situ heating at 65 C resulted in aggregation of spherical nanoparticles into nanosquares. Finally, simultaneous variation of CTAB and temperature (in situ and ex situ) generated nanoflakes, nanoflowers, nanosquares and branched nanorods. Highly anisotropic nano-flakes, nano-flowers, nano-squares and branched-nanorods structures display distinct optical absorption and emission behavior.

Effects of laser fluence on the characteristics of copper sulfide (CuS) nanoparticles (NPs), produced by laser ablation method have been investigated experimentally. CuS nanoparticles were synthesized by the pulsed laser ablation of a high purity copper bulk in dimethyl sulfoxide (DMSO). Pulses of a Q-switched Nd:YAG laser of 1064 nm wavelength at 7 ns pulse width and different fluences were employed to irradiate the Cu solid target in DMSO. The Effects of laser fluence on the size, morphology, and structure of produced nanoparticles have been studied. Results show that the size distribution of the generated CuS nanoparticles was augmented by increasing the laser fluence. The rate of CuS nanoparticles production was increased by increasing the laser fluence. The bandgap energy for CuS nanoparticles was calculated to be 3.77–3.94 eV.

Silicon carbide (SiC) has been widely used in various technological applications, including power devices, light-receiving devices, and light-emitting devices. Several methods for fabricating SiC particles with nanometer dimensions have been reported, including carbo-thermal reduction of silica, chemical vapor deposition, laser pyrolysis, and microwave irradiation. To develop a new and simple method for fabricating SiC nanoparticles, we investigated the possibility of using femtosecond-laser ablation. In this paper, we report the formation of SiC nanoparticles by femtosecond-laser ablation on silicon immersed in hexane. By using a high-peak-power laser that can achieve extremely high temperatures and pressures on the silicon surface, SiC nanoparticles were successfully fabricated via ablation in hexane. In our experiments, femtosecond pulses from a Yb-fiber laser were used to irradiate to silicon single crystal. The laser was focused onto a spot on the silicon surface. After ablation, we evaluated the particles on the target substrate and particles in the irradiated hexane. Scanning electron microscopy revealed that the particles range in size from 100 to 400 nm. X-ray diffraction analysis indicated that the nanoparticles might be SiC. The characteristic X-ray photoelectron spectroscopy peaks of nanoparticles were Si-2p (100.1 eV) and C-1s (282.9 eV), which are identical to the characteristic peaks of SiC (John et al. in Handbook of X-ray photoelectron spectroscopy, Physical Electronics, Eden Prairie, 1995; Hijikata et al. in Appl Surf Sci 184:161–166, 2001; Shen et al. in Chem Phys Lett 375:177–184, 2003). We also used transmission electron microscopy and electron energy-loss spectroscopy to evaluate particles from the irradiated hexane. Such a simple method of fabricating SiC nanoparticles by femtosecond-laser ablation may open new possibilities in the development of growth techniques for SiC.

The distinctive feature of upconverting compounds to absorb and emit light in the near-infrared region has made upconverting nanoparticles of great interest in various application fields. Nevertheless, these colloids show a highly hydrophobic behavior, and therefore, the use of a proper stabilizing agent is necessary in most cases. Although few chemical techniques for colloid stabilization are available, it is still difficult to achieve a fully reproducible synthesis method for stable upconverting nanoparticle colloids. In this work, upconversion 18 %Yb:1 %Er:NaYF4 nanoparticles were produced by ultrafast pulsed laser ablation in a water and 2-[2-(2-methoxyethoxy)- ethoxy]acetic acid (MEEAA) environment to assess the stabilization effect of the surfactant on the nanoparticle colloid properties. The effects of the laser fluence and MEEAA concentration on the nanoparticles′ properties were investigated by TEM, EDS, and emission spectra analyses. The results show that ultrashort pulsed laser ablation in liquid allows generating highly spherical nanoparticles with conserved stoichiometry and optical properties. Moreover, it is possible to obtain colloids with significantly higher stability and preserved optical properties by one-step PLAL processes directly in the MEEAA environment.

We report the electrochemistry of gold nanoparticles (AuNPs), prepared by Laser Ablation Synthesis in Solution (LASiS), via the electrocatalytic oxidation of glucose upon single nanoparticle collisions at inert microelectrodes. Spherical AuNPs with diameters in the range 20–30 nm, as determined by transmission electron microscopy, were synthesized by LASiS of a gold plate immersed in water. Nanoparticle collisions were electrochemically detected through the AuNP-catalysed oxidation of glucose at carbon fiber microelectrodes in alkaline solution, enabling the electrocatalytic detection of single AuNPs. This approach provides a basis for detecting and understanding the electrocatalytic properties of pristine nanoparticles in aqueous solutions. Keywords: Gold nanoparticles, Laser ablation, Glucose, Electrocatalysis, Nano-impact

Colloidal solution of iron oxide nanoparticles is synthesized by nanosecond pulsed laser ablation (Nd:YAG laser, 1064 nm, 7 ns, and 180 mJ) of a metallic iron target in water, and nanocrystalline powder is prepared from this solution by vacuum drying. A composition and structure of the material obtained are investigated by methods of electron microscopy, x-ray diffraction, and optical spectroscopy. It is established that oxide particles with average size of about 5 nm and Fe3O4 magnetite structure are mainly formed during ablation. Preliminary investigation of magnetic properties of the prepared nanoparticle powders shows that they can be in ferromagnetic and/or superparamagnetic states.

Bare nanoparticles synthesized by laser ablation in water have found their application in catalysis, spectroscopy and biomedical research fields. In this perspective, how to efficiently produce stable nanoparticles with controllable size is an important topic and has attracted a lot of interests. Here, we introduce a multiple-pulse laser as the ablation source. By changing the number of sub-pulses, the average size of nanoparticles can be tuned in a broad range from ∼120 nm to ∼4 nm. The demonstration in this article may offer a new approach to fabricate ultrafine nanostructures and also help the scientific study of the mechanism in laser ablation.

Laser ablation in liquids is actively used for generation of clean colloidal nanoparticles with unique shapes and functionalities. The fundamental mechanisms of the laser ablation in liquids and the key processes that control the nanoparticle structure, composition, and size distribution, however, are not yet fully understood. In this paper, we report the results of first atomistic simulations of laser ablation of metal targets in liquid environment. A model combining a coarse-grained representation of the liquid environment (parameterized for water), a fully atomistic description of laser interactions with metal targets, and acoustic impedance matching boundary conditions is developed and applied for simulation of laser ablation of a thin silver film deposited on a silica substrate. The simulations, performed at two laser fluences in the regime of phase explosion, predict a rapid deceleration of the ejected ablation plume and the formation of a dense superheated molten layer at the water-plume interface. The water in contact with the hot metal layer is brought to the supercritical state and transforms into an expanding low density metal-water mixing region that serves as a precursor for the formation of a cavitation bubble. Two distinct mechanisms of the nanoparticle formation are predicted in the simulations: (1) the nucleation and growth of small (mostly ⩽10nm) nanoparticles in the metal-water mixing region and (2) the formation of larger (tens of nm) nanoparticles through the breakup of the superheated molten metal layer triggered by the emergence of complex morphological features attributed to the Rayleigh-Taylor instability of the interface between at the superheated metal layer and the supercritical water. The first mechanism is facilitated by the rapid cooling of the growing nanoparticles in the supercritical water environment, resulting in solidification of the nanoparticles located in the upper part of the mixing region on the timescale of nanoseconds. The computational prediction of the two mechanisms of nanoparticle formation yielding nanoparticles with different characteristic sizes is consistent with experimental observations of two distinct nanoparticle populations appearing at different stages of the ablation process.

Cubic phase zinc peroxide nanoparticles (ZnO 2 NPs) with an average diameter of ca. 9–15 nm have been synthesized via a fast nanosecond pulse laser ablation in liquid technique (PLAL), using H 2 O 2 aqueous solution as the ablation media and a 532 nm pulsed laser as the irradiation source and low-cost zinc powder as the solid target. Both the laser energy and ablation time potentially have a substantial influence on the formation of ZnO 2 NPs. Due to its relatively high oxidation level as well as its hydrophilic wetting behavior, the as-synthesized ZnO 2 NPs exhibit efficient photocatalytic degradation ability of Rhodamine B (RB) whilst remaining stable to photodegradation. The possible mechanisms of the photocatalytic behavior have been discussed in what follows.

Performance enhancements in next-generation electrochemical energy storage/conversion devices require the design of new classes of nanomaterials that exhibit unique electrocatalytic and supercapacitive properties. To this end, we report the use of laser ablation synthesis in solution (LASiS) operated with cobalt as the target in graphene oxide (GO) solution in tandem with two different post-treatments to manufacture three kinds of hybrid nanocomposites (HNCs) namely, (1) Co3O4 nanoparticle (NP)/reduced graphene oxide (rGO), (2) Co3O4 nanorod (NR)/rGO, and (3) Co3O4 NP/nitrogen-doped graphene oxide (NGO). FTIR and Raman spectroscopic studies indicate that both chemical and charge-driven interactions are partially responsible for embedding the Co3O4 NPs/NRs into the various GO films. We tune the selective functionalities of the as-synthesized HNCs as oxygen reduction reaction (ORR) catalysts and/or supercapacitors by tailoring their structure–property relationships. Specifically, the nitrogen doping in the NP/NGO HNC samples promotes higher electron conductivity while hindering aggregation between 0D CoO NPs that are partially reshaped into Co3O4 nanocubes due to induced surface strain energies. Our results indicate that such interfacial energetics and arrangements lead to superior ORR electrocatalytic activities. On the other hand, the interconnecting 1D nanostructures in the NR/rGO HNCs benefit charge transport and electrolyte diffusion at the electrode–electrolyte interfaces, thereby promoting their supercapacitive properties. The NP/rGO HNCs exhibit intermediate functionalities towards both ORR catalysis and supercapacitance.

The search for new plasmonic nanostructures has received significant attention recently, owing to applications in diverse fields of nanoscience and nanotechnology, and being of interest for the life sciences. Metallic nanoparticles (NP) can strongly absorb and scatter light due to their ability to support localized surface plasmon resonances (LSPR) and, therefore, play an important role in plasmonic-based techniques such as surface enhanced Raman scattering (SERS) and metal-enhanced fluorescence (MEF). Interestingly, most research in the field is still confined to Ag, Au, and less intensively Cu nanostructures, and there is an open field for the investigation of other elements such as the poor metals. In this work, we investigate plasmonic properties of different metal nanoparticles, including the post-transition metals Bi, In, Pb, and Sn; the metalloid Sb; the transition metals Ni and Co; and the metal alloy Terfenol-D. All these nanoparticles were experimentally tested for LSPR and SERS, and our results indicate SERS responses and enhancement factors comparable to the ones obtained with gold NP. The nanoparticles used in this study were produced via laser ablation synthesis in solution (LASiS) and characterized by UV-Vis optical absorption, dynamic light scattering (DLS), transmission electron microscopy (TEM), atomic force microscopy (AFM) and surface area electron diffraction (SAED). These laser-synthesized NP present increased LSPR in the near UV spectral region, yet also reveal multi-peak LSPR extending towards the visible, an interesting feature to be considered in the development of plasmonic sensors. For the Raman experiments, several organic and biological molecules were tested, and SERS activity was demonstrated for diverse combinations of NP and test-analytes at varying concentrations, down to single molecule detection.

We demonstrate the catalytic performance of perovskite-based oxygen reduction reaction (ORR) catalyst based on LaMnO 3+δ nanoparticles (LMO NPs) prepared using the laser ablation synthesis in solution method. The ORR catalytic activity of the post-annealed LMO NPs was similar to that of commercial Pt/C catalysts due to the increased surface area as well as the perovskite crystalline structure of the LMO NPs. The mass and specific activities of the LMO NP catalyst annealed at 800 °C were 20 and 2.2 times higher than those of the bulk LMO, respectively. In a chronoamperometric stability test, our LMO NP catalyst (annealed at 800 °C) outperformed the Pt/C catalyst.

YVO 4 :Eu 3+ 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 YVO 4 :Eu 3+ 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 YVO 4 was obtained in this study.

We report about the chemical activity of Gd and Si nanoparticles in the mixture of their colloidal solutions. It was found that mixing of two colloids prepared by laser ablation technique results in the chemical interaction between nanoparticles and formation of silicide phases at room temperature. The phase composition of the resulting products was found to be dependent on the mixing order.

The importance of actinide based nano-structures is well known in the area of biology, nuclear medicine and nuclear industry. Pulsed laser ablation in liquid is recognised as an attractive technique for production of nano-structures of different metals and metal oxides with high purity. In this paper, we report synthesis of uranium-di-oxide nanoparticles by pulsed laser ablation in ethanol. The second harmonic emission of an electro-optically Q-switched nano-second Nd-YAG laser was used as the coherent source here. The structural and optical properties of the fabricated uranium-di-oxide nanoparticles were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive analysis of X-rays (EDX) and UV–Vis–NIR spectrophotometry. The mean size of the particles was found to be dependent on the laser ablation parameters in particular with laser fluence. XRD and TEM analysis confirmed the phase of the synthesised material as pure crystalline uranium-di-oxide with face centred cubic structure. UV–Vis–NIR absorption spectra of the colloidal solution revealed high absorption in the UV regime.

Nanoparticles of palladium and its oxides are synthesized on carbonic materials via the laser ablation and deposition of metals in electric fields. Studies of the materials show it is possible to control the crystallinity, size, and chemical state of nanoparticles without changing the laser beam parameters.

Amine-terminated, ultra-small silicon nanoparticles (Si-NPs) were prepared in one step avoiding the conventional chemical or thermal treatment of Si surface, by introducing organosilane in Si-NPs colloidal solution freshly prepared by ultra-fast laser ablation of silicon target in deionized water. Surface chemistry studies of Si-NPs conducted by Raman and Fourier infrared spectroscopy demonstrated the hydroxyl-terminated surface of Si-NPs. The reactivity of hydroxyl-terminated surface with aminopropyltriethoxysilane in aqueous solution was investigated. Electron microscopy, dynamic light scattering, infrared spectroscopy and stability studies confirmed the successful functionalization of Si-NPs leading to 5nm Si dots covered by aminopropyltriethoxysilane thick layer. Detailed infrared spectroscopy analysis of the Si-O-Si region as a function of immersion time revealed the formation of interfacial Si-O bonds between the organosilane and hydroxyl groups of the nanoparticles. The biocompatible Si nanostructure containing amine functional group prepared using a one-step green protocol opens the route for biomedical applications and successful translation into clinical setting, as bio-labels, contrast agents and vector delivery.

The method of pulsed laser ablation in liquid was used to synthesize dispersions of cerium oxide nanoparticles when subjecting a metallic cerium target in water and alcohol to basic frequency radiation of the nanosecond Nd:YAG laser (1064 nm, 7 ns, 20 Hz). Researchers have studied the effect of laser radiation parameters, duration of impact, and optical scheme of experiment on the ablation process. The average rate of nanoparticle production was 50 mg/h in water and 25 mg/h in alcohol. Researchers have studied the size characteristics and crystalline structure of the nanoparticles produced. The particles have bimodal size distribution with 6 nm and 25 nm maximums. The average crystallite size is 17–19 nm. The crystalline structure of nanoparticles, namely cubic cerium oxide (fluorite structure), space group Fm-3m, is confirmed by the X-ray diffraction data, as well as optical absorption spectra and Raman spectroscopy.

Nanoparticles NPS of cadmium oxide CdO were generated by laser ablation of a solid target (cadmium) in polyvinylpyrrolidone (PVP) solution. CdO colloidal nanoparticles have been synthesized by laser ablation Nd:YAG (1064 nm, 100 pulses, pulse energy= 400 mJ) when the solid target CdO was immersed in PVP. Structure, topography and optical properties of the CdO nanoparticles NPS have been studied using X-ray diffraction (XRD), atomic force microscope (AFM) and the UV-Vis absorption respectively.

Dispersions of cerium oxide nanoparticles in water, ethanol, and water-ethanol solution were synthesized for the first time using laser ablation of metallic target. The fundamental harmonic of nanosecond Nd:YAG laser was used. Nanocrystalline powders of cerium oxide were obtained from the dispersions. The average size of the crystallites was 17-19 nm. Phase composition of nanoparticles was confirmed by X-ray diffraction and Raman spectroscopy. It was found that carbon present on the surface of CeO2 particles. The materials obtained may be used as catalyst carriers for CO oxidation, and as active components of sunscreen cosmetic products.

Cubic Cu(1.4)S nanoparticles were synthesized on a large scale by laser ablation of salt powder dispersed in an organic solvent. A metastable Cu(1.4)S phase was formed at high temperature in a reductive solvent and was maintained at room temperature due to the quenching effect of the pulsed laser. The cubic Cu(1.4)S nanoparticles show good stability after being exposed to ambient atmosphere for as long as 1 month.

Colloidal solutions of Pd nanoparticles were produced by laser ablation of solids in liquids (LASL) technique. Two different lasers operating at 1064 and 532 nm of wavelength to ablate a Pd foil submerged in water were used. The properties of the obtained nanoparticles were studied and the influence of the wavelength on the nanoparticle size was discussed. The nanoparticles formation mechanism is discussed and compared with the results obtained in previous work using continuous wave (CW) and long pulses lasers. The obtained nanoparticles were characterized by means of transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM) and UV/VIS absorption spectroscopy. The obtained nanoparticles consisted of crystalline Pd nanoparticles with rounded shape and strong tendency to agglomeration. The size distribution of the nanoparticle range from few nanometers to 40 nm together with the presence of occasional large particles when the infrarred (IR) laser was used.

Cerium-dioxide nanoparticles are prepared by laser ablation, and their structure is studied by transmission electron microscopy and X-ray-diffraction analysis. The semiquantitative elemental composition is determined by electron energy-loss spectroscopy. Based on the spectral data obtained before and after annealing of particles, the significant oxygen-vacancy concentration in the structure of ablated CeO2 nanoparticles is established.

We report on Terfenol-D nanoparticle (TDNP) production by Laser Ablation Synthesis in Solution (LASiS). Nanoparticle shape and size distribution were analyzed by Transmission Electron Microscopy (TEM) and Dynamic Light Scattering (DLS). Colloidal optical properties were studied by means of UV-Vis spectroscopy, and Raman scattering. The nanoparticles present a spherical shape with average size of 17 nm. Interesting results have been found regarding absorbance peak shift in the UV-Vis experiment, a dependence on colloidal suspension concentration. A surface enhanced Raman spectroscopy (SERS) of the amino acid Proline (Pro) using TDNP as substrate was performed and compared with previous studies. An expected intensification on several Proline peaks was observed, as well as a strong blue-shift of peaks assigned to CH and CH 2 stretching vibrations. These results indicate Terfenol-D nanoparticles might be a promising material as SERS agents, with possible applications in nanophotonics, e.g., as biosensors.

Silver nanoparticles (AgNPs) are well-known for their antimicrobial effects and several groups are proposing them as active agents to fight antimicrobial resistance. A wide variety of methods is available for nanoparticle synthesis, affording a broad spectrum of chemical and physical properties. In this work, we report on AgNPs produced by laser ablation synthesis in solution (LASiS), discussing the major features of this approach. Laser ablation synthesis is one of the best candidates, as compared to wet-chemical syntheses, for preparing Ag nano-antimicrobials. In fact, this method allows the preparation of stable Ag colloids in pure solvents without using either capping and stabilizing agents or reductants. LASiS produces AgNPs, which can be more suitable for medical and food-related applications where it is important to use non-toxic chemicals and materials for humans. In addition, laser ablation allows for achieving nanoparticles with different properties according to experimental laser parameters, thus influencing antibacterial mechanisms. However, the concentration obtained by laser-generated AgNP colloids is often low, and it is hard to implement them on an industrial scale. To obtain interesting concentrations for final applications, it is necessary to exploit high-energy lasers, which are quite expensive. In this review, we discuss the pros and cons of the use of laser ablation synthesis for the production of Ag antimicrobial colloids, taking into account applications in the food packaging field.

Nanoparticles of the post-transition metals, In, Sn, Pb, and Bi, and of the metalloid Sb were produced by laser ablation synthesis in solution (LASiS) and tested for localized surface plasmon resonances (LSPR) and surface-enhanced Raman scattering (SERS). The nanoparticles were characterized by UV-Vis optical absorption, dynamic light scattering (DLS), and transmission electron microscopy (TEM). Several organic and biological molecules were tested, and SERS activity was demonstrated for all tested nanoparticles and molecules. The Raman enhancement factor for each nanoparticle class and molecule was experimentally determined. The search for new plasmonic nanostructures is important mainly for life sciences-related applications and this study expands the range of SERS active systems.

Multimodal contrast agents offer new interesting diagnostic possibilities, summing the benefits of multiple imaging techniques. Magnetic resonance and optical imaging are complementary techniques. The first allows total body screening, even though it suffers from low spatial resolution and needs high loadings, whereas the second shows lower penetration, but bright signals, and a higher spatial resolution and needs lower loadings. We present a plasmonic nanosystem as a MRI (magnetic resonance imaging) and SERRS (surface enhanced resonance Raman scattering) multimodal contrast agent. Naked gold nanoparticles, obtained by laser ablation synthesis in solution, are organized as a highly efficient SERRS substrate with a naphthalocyanine reporter and functionalized with a MRI contrast agent with a newly synthesized 3DOTA-PEG polymer, with a high GdIII loading. As a proof of concept, in vivo and ex vivo MRI and SERRS experiments are also performed. The plasmonic property of the nanosystem is then exploited to show its usefulness for localized hyperthermia.

This study proposes a method for preparing high-concentration silica-coated Au (Au/SiO2) nanoparticles in colloidal solution from 1.5 × 10−3 M hydrogen tetrachloroaurate (III) trihydrate as the Au source and 1.0 × 10−2 M sodium citrate as the reducing reagent. The colloidal solution is applied to X-ray computed tomography (CT) imaging of mouse tissue. The Au nanoparticles in the colloidal solution had a diameter of 18.9 nm, and the Au concentration reached 1.5 × 10−3 M. The Au nanoparticles were silica-coated by modifying their surfaces with (3-aminopropyl)trimethoxysilane (APMS), then depositing silica nuclei generated by a sol–gel reaction of tetraethyl orthosilicate (TEOS) in water/ethanol initiated with sodium hydroxide (NaOH) on the surface modified with APMS. A colloidal solution of Au/SiO2 core–shell particles (silica shell thickness = 19.7 nm) was formed in a final as-prepared solution of 2.7 × 10−4 M Au, 2.0 × 10−5 M APMS, 24 M H2O, 1.9 × 10−3 M NaOH, and 4.1 × 10−3 M TEOS. The Au in the as-prepared colloidal solution was further concentrated to 0.27 M by salting-out and centrifugation. The CT value of the concentrated Au/SiO2 colloidal solution was 2.52 × 103 Hounsfield units, double that of a commercial X-ray contrast agent with the same I concentration as the Au concentration. When injected into mouse tissue, the Au/SiO2 colloidal solution demonstrated good imaging capability.

In this study, colloidal tungsten oxide nanoparticles were fabricated by pulsed laser ablation of tungsten target using the first harmonic of a Nd:YAG laser (1064 nm) in deionized water. After ablation, a 0.33 g/lit HAuCl4 aqueous solution was added into as-prepared colloidal nanoparticles. In this process, Au3+ ions were reduced to decorate gold metallic state (Au0) onto colloidal tungsten oxide nanoparticles surface. The morphology and chemical composition of the synthesized nanoparticles were studied by AFM, XRD, TEM and XPS techniques. UV–Vis analysis reveals a distinct absorption peak at ∼530 nm. This peak can be attributed to the surface plasmon resonance (SPR) of Au and confirms formation of gold state. Moreover, X-ray photoelectron spectroscopy reveals that Au ions’ reduction happens after adding HAuCl4 solution into as-prepared colloidal tungsten oxide nanoparticles. Transmission electron microscope shows that an Au shell has been decorated onto colloidal WO3 nanoparticles. Noble metal decorated tungsten oxide nanostructure could be an excellent candidate for photocatalysis, gas sensing and gasochromic applications. Finally, the gasochromic behavior of the synthesized samples was investigated by H2 and O2 gases bubbling into the produced colloidal Au/WO3 nanoparticles. Synthesized colloidal nanoparticles show excellent coloration contrast (∼80%) through NIR spectra.

Silver nanoparticles with acetonitrile ligands are produced in a laser ablation flow reactor. Excimer laser ablation produces gas phase metal clusters which are thermalized with helium or argon collisions in the flowtube, and reactions with acetonitrile vapor coordinate this ligand to the particle surface. The gaseous mixture is captured in a cryogenic trap; warming produces a solution of excess ligand and coated particles. TEM images reveal particle sizes of 10–30 nm diameter. UV–vis absorption and fluorescence spectra are compared to those of standard silver nanoparticles with surfactant coatings. Deep-UV ligand absorption is strongly enhanced by nanoparticle adsorption.

Laser ablation in liquids is especially adapted to produce nanoparticles free of any contamination as suited for biological and medical applications. A KrF Excimer laser delivering an UV light at 248 nm and operating at low fluence ( F ~0.5 J/cm 2 ) was used to irradiate a micro-sized powder of selenium dispersed into a de-ionized water solution. To avoid any agglomeration of the selenium nanoparticles during the irradiation, surfactants (SDS and CTAB) were added to the solution and their efficiency was compared. The concentration of surfactants had to be chosen around the critical micellar concentration to produce small selenium nanoparticles (

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.

In the literature many investigations on colloidal stability and size control of gold nanoparticles are shown but less for ligand-free palladium nanoparticles, which can be promising materials in various applications. Palladium nanoparticles are perspective materials for a manifold of energy application like photo- and electrocatalysis or hydrogen storage. For this purpose, size-controlled nanoparticles with clean surfaces and facile immobilization on catalyst supports are wanted. Laser ablation in saline solution yields ligand-free, charged colloidal palladium nanoparticles that are supported by titania and graphene nanosheets as model systems for photo- and electrocatalysis, respectively. By adjusting the ionic strength during laser ablation in liquid, it is possible to control stability and particle size without compromising subsequent nanoparticle adsorption of supporting materials. A quantitative deposition of nearly 100% yield with up to 18 wt% nanoparticle load was achieved. The average size of the laser-generated nanoparticles remains the same after immobilization on a support material, in contrast to other preparation methods of catalysts. The characterization by X-ray photoelectron spectroscopy reveals a redox reaction between the immobilized nanoparticles and the graphene support.