Liquid Laser Research Articles

On the in situ formation of carbenes in ionic liquids

Ionic liquids are considered as tunable designer liquids that may provide the perfect environment or active species for chemical reactions. N-Heterocyclic carbenes are known to be important organocatalysts enabling novel and specific routes for general synthetic strategies. There has been a lot of speculation about the role, stability, and the existence of in situ formed carbenes in ionic liquids. Here, we show that cation stabilised carbenes can exist in room temperature ionic liquids as reactive intermediates detectable with liquid microbeam IR laser desorption mass spectrometry. The experimental results were supported by density functional theory. Intriguingly, we also found that carbenes appear to correlate with and may be the origin of strong chemisorption of carbon dioxide in ionic liquids.

Structural and Fluorescence Properties of TiO2/Ag Nanoparticles Bilayers

The optical properties of the TiO2 / Ag hybrid nanoparticles were improved as the particles were prepared with a pulsed liquid laser ablation (PLAL) technology. The effect of number of pulses (450) on the structural and optical properties of nanoparticles prepared in distilled water (DW) as growth media was examined using a Q-Switched Nd-YAG laser with wavelength (1064 nm), ablation energy (530 mJ) and repetition rate (1Hz). The distance between the target and the lens (10 cm). Several were used for the diagnosis such as X-ray diffraction analysis, fourier infrared transformations, TEM assays and fluorescence of the prepared samples. The results of X-ray diffraction analysis of the silver nanoparticles deposited on a glass slide showed that the crystal system is cubic and polycrystalline, with the direction being dominated by [111] at the level of the crystals. The results of X-ray diffraction analysis of a solution of titanium dioxide nanoparticles deposited on a glass slide revealed the presence of a quadrangular crystal system, indicating the presence of titanium dioxide particles in (rutile), and that the prevailing trend for crystalline levels is [110]. The functional groups of (TiO2 / Ag) were determined in the liquid medium by the (FTIR) technique. Also, TEM images showed the presence of nanoparticles and microparticles in an almost spherical shape. The fluorescence measurement of (TiO2 / Ag) hybrid particles showed that through the graph the peak values of (284.1) and (418.3) nm. This is roughly identical to the absorption spectrum results of a hybrid silver and titanium dioxide nanoparticle solution.

Synthesis Emission Spectra of (LIPS) Technique for Cu, Ag Nanoparticles and their Antibacterial Activity

A spectroscope presents the optical emission spectroscopy (OES) technique on laser-produced copper and silver plasmas. The optical emission spectrum technique was used to analyzes the spectrum arising from the Cu, Ag Laser Nd: YAG plasmas with a wavelength of (1064) nm, a span of (10) ns, and a focal length of (10) cm in the energy range (300-800) mJ. The electron temperature (Te) was determined while the Saha-Boltzmann equation was used to measure the electron density (ne). Other plasma parameters, (λD), (fp), (ND), were also measured. For various energies, the plasma spectrum was registered copper and silver. Q-switched Nd: YAG liquid laser ablation technique (PLAL) was used to produce nanoparticles (NPs), silver, and copper particles using distilled water at room temperature at different energies (300-600-800) mJ. With a constant wavelength (1064nm). At a constant frequency (6Hz), 300 laser pulses were used to ablate the target placed in distilled water to study the effect of these materials in inhibiting bacteria. Bacteria were used (Staphylococcus). This study showed that (Ag-NPs) and (Cu-NPs) that are synthesized by laser ablation have a great effect on Staphylococcus (antibiotic-resistant) bacteria.

Synthesis of Cinnamon Nanoparticles by Using Laser Ablation Technique

The natural polyphenolic compound that cinnamon contains is well known for its various biological activities, a broad variety of pharmacological and therapeutic properties. Diversified biomedical and pharmacological applications benefit from organic nanoparticles with controlled properties. Bioactive and non-toxic, cinnamon nanoparticles (CNPs) can be effective antibacterial agents. Driven by this idea, we prepared spherical CNPs using liquid (PLAL) pulse laser ablation technique and defined those NPs. Using Q-switched Nd : YAG With a wavelength of 1064 nm pulse laser of constant energy 500 mj , And different laser pulses ( 250 , 500 , 750 , 1000 ) pulse /sec a pure cinnamon target submerged in liquid ethanol (5 mL) was ablated. The results on the composition, morphology and optical properties of as-grown CNPs of differing laser fluence were determined. Samples were described through Fe-SEM , UV-Vis , FTIR , The synergy between ethanol as liquid growth media and fundamental laser wavelength has been due to certain distinctive characteristics of CNPs. It has been developed that the spherical CNPs achieved in the suspension of ethanol could be beneficial for antioxidant purposes.

Effect of liquid media and laser energy on the preparation of Ag nanoparticles and their nanocomposites with Au nanoparticles via laser ablation for optoelectronic applications

The nanostructured materials from Ag and Au@Ag core/shell bimetallic were synthesized by pulsed infrared laser ablation process in different liquid media technique in just one-pot step. By varying the surrounding media by metallic precursor solution and the laser energy, the monometallic nanoparticles were changed to bimetallic nanocomposites in a form of core/shell structure with tuning their shell thickness. The prepared nanostructured materials were examined by different spectroscopic techniques to inform their physicochemical properties. The characterization techniques proved that the crystallinity of prepared samples. Besides, the bimetallic nanocomposite structure has a core/shell form with Au in the core and Ag in shell. Also, as the laser intensity raises, the Ag-shell’s thickness grows, and the core/shell diameter increases, which was affected in their linear and nonlinear optical properties. Their linear properties were investigated depended on Mie theory. Besides, the nonlinear optical parameters were determined by Z-scan technique, which demonstrated that the nonlinear optical properties of a shell can be tuned depending on their thickness. The prepared core/shell nanocomposites with different particle sizes confirmed the capability for possible application in optoelectronic applications as good optical limiting materials.

Influence of liquid media and laser energy on the production of MgO nanoparticles by laser ablation

Nano and micro-sized metal particles are interesting solutions for several applications, from electronics to biomedical fields. In recent years, MgO has been gaining attention due to its nontoxicity and antibacterial activity, making this an interesting material for implants coating for instance.This study aims the fabrication/preparation of nanoparticles by laser ablation in liquid from the Mg bulk. The influence of liquid media and laser energy on the morphology, size and properties of the obtained nanoparticles was assessed. A Nd:YAG nanosecond laser of 1064 nm of wavelength at different laser energies was employed to irradiate Mg target in three environments (distilled water+SDS, ethanol and propanol). Ultraviolet–visible (UV–vis) absorption spectrophotometry, scanning electron microscopy with a transmission electron detector (STEM) and transmission electron microscopy (TEM) were used for characterizing the obtained particles, viz. particles’ mean size and size distribution. The composition of the obtained nanoparticles was analyzed by SAED patterns. The results showed that the characteristics of the obtained nanoparticles were prominently influenced by varying laser energy and liquid medium. The smaller particles are obtained when using ethanol and propanol (having 16.7 nm and 15.3 nm respectively), as compared to distilled water+surfactant.

Investigation of photophysical properties of ternary Sm(III) complexes

Three asymmetric Sm(III) complexes featuring 6-Fluoro-4-oxo-4H-1-benzopyran-3-carboxaldehyde, 2,2’-Biquinoline, 4-Methyl-1,10-Phenanthroline, and Bathocuproine were prepared and characterized. The sharp peaks in powder XRD suggest high crystallinity in the complexes. The thermal behavior of complexes was studied under an inert atmosphere using thermogravimetric analysis. The Sm(III) samples deliver excellent luminescent properties in powder (red emission) and solution (orange emission). The decay time was best fitted with the mono-exponential function. The good PL characteristics of complexes suggest their potential applications in solid-state lighting, optical devices, liquid lasers.

Liquid metallic laser ultrasound transducer for high-temperature applications

This study aims to investigate a laser ultrasound (LUS) transducer for high-temperature (>100 °C) applications. For decades, many researchers have investigated efficient LUS transducers, yet studies on laser ultrasound transducers capable of performing at the high-temperature condition are rarely found in the literature. Most current LUS transducers still utilize a polymer-based composite material, that is, not stable at varying temperature conditions. This study introduces a liquid metallic (LM) LUS transducer that utilizes field's metal, which has a high thermal expansion (∼3 × 10−4 K−1). We hypothesized that such a high thermal expansion of the liquid metal can effectively produce laser-generated ultrasound waves, substituting for conventional polymer-based transducers. A numerical simulation predicted that the LM LUS transducer would produce higher LUS intensity (∼22 dB) than that without the LUS transducer. Experiment results confirmed that the LM transducer effectively intensifies the ultrasound wave signals, obtaining a signal-to-noise gain over 30 dB. Moreover, the transducer was found capable of transmitting detectable wave packets in relatively high-temperature conditions (∼400 °C), while conventional candle soot nanoparticle-polydimethylsiloxane could not perform stably at these elevated temperatures. The investigations introduced in this article are scientifically significant since we demonstrated the engineering feasibility of liquid metallic materials for LUS transducers.

Synthesis and analysis of cupper nanoparticles produced by laser

Cupper nanoparticles are generated by using Nd:YAG laser nanosecond pulses using the liquid laser ablation technique. Nd:YAG of 6 and 10 nanoseconds pulse length with variable energy in the range are the two systems used (700-760 mJ ).The formation of cupper nanoparticles has been abolished using TEM with identical size distribution It has also been observed that when identical laser parameters are used, the average nanoparticles sizes of 80 and 120 nm for cupper are used.Furthermore, to approximate the temperature distributions for both cupper nanoparticles, the theoretical Mie-Gans model was used. Another factor that has been found is that the maximum temperature for gold nanoparticles is between (1000 K) and (1400 K), especially for the preparation of nanoparticles in the presence of 10 ns Nd:YAG.

Characterization of aluminum-based coatings after short term exposure during irradiation campaign in the LVR-15 fission reactor

Protective aluminum-based coatings represent a promising anti-permeation and anti-corrosion barrier for breeding blanket systems developed for European DEMO fusion reactor. Following the prior in-depth characterizations, selected coating candidates were subjected to a combined test consisting of contact with liquid Pb-16Li, its repeated in-situ solidification and re-melting, tritium permeation during gamma and neutron irradiation in the LVR-15 fission reactor. During the sample exposure in the reactor, the temperature of Pb-16Li was between 300 and 425 °C. The irradiation damage averaged over the sample volume estimated by FISPACT code was limited to 0.037 dpa. This article presents post-irradiation characterization of cylindrical Eurofer97 samples coated by electro-chemical X-metal deposition from ionic liquid (ECX) and pulsed laser deposition (PLD) techniques. The coating damage relative to a reference uncoated sample is discussed.

Thermo-Fluid Design Simulation of Nd3+ POCl3 Transverse Flow Liquid Laser Cavity

Abstract Computational fluid dynamics (CFD) based thermal design of a transverse flow optical cavity is carried out for 1 kW Nd3+ POCl3 liquid laser source to investigate temperature and velocity distribution in the optical pumping region of the cavity. Temperature gradient and turbulence both affect the refractive index of the liquid gain medium, which results in optical path difference (OPD), divergence and hence, poorer quality of the laser beam. The main purpose of this design is to achieve uniform flow and least temperature gradient in the optical pumping region so that the optical path difference can be minimized and a good beam quality can be achieved. CFD model has been developed for carrying out thermo-fluid simulations for this thermal system and based on these simulations, an optimum geometry of inlet ports along with their position from optical pumping region have been proposed. A user defined function (UDF) is incorporated for the input of spatially varying heat source term in each cell of the optical pumping region of the cavity. Variations in refractive index and optical path difference are estimated from the temperature data using another UDF. Simulation reveals that mass flowrate between 1.5 kg/s and 2.0 kg/s maintains the optical homogeneity of gain medium. Preliminary experiments have been carried out to demonstrate the effect of flowrate on the beam divergence and thereby exhibiting the importance of present simulation work.

Diode pumping of liquid crystal lasers

Liquid crystal lasers are typically pumped with Q-switched lasers, which provide the short pulse durations necessary to produce band-edge liquid crystal laser emission. However, the current cost and bulk of the pump laser, relative to the liquid crystal component, limit the application potential of liquid crystal laser technology. A low-cost and compact alternative pump source has often been discussed within the liquid crystal laser community but has not yet been demonstrated. In this paper, a 445 nm laser diode was integrated with carefully selected electronics in an attempt to reproduce equivalent pump conditions to that achieved from a Q-switched laser, and then used to pump a liquid crystal laser. Successful band-edge lasing was achieved, demonstrating, for the first time, a clear threshold and single mode, narrow linewidth emission. Red, green and blue outputs from different liquid crystal lasers were also realised when pumped with the same laser diode, demonstrating the broad wavelength selectivity of liquid crystal lasers using a single low-cost, compact device.

Discrimination of ablation, shielding, and interface layer effects on the steady-state formation of persistent bubbles under liquid flow conditions during laser synthesis of colloids

Over the past decade, laser ablation in liquids (LAL) was established as an innovative nanoparticle synthesis method obeying the principles of green chemistry. While one of the main advantages of this method is the absence of stabilizers leading to nanoparticles with “clean” ligand-free surfaces, its main disadvantage is the comparably low nanoparticle production efficiency dampening the sustainability of the method and preventing the use of laser-synthesized nanoparticles in applications that require high amounts of material. In this study, the effects of productivity-dampening entities that become particularly relevant for LAL with high repetition rate lasers, i.e., persistent bubbles or colloidal nanoparticles (NPs), on the synthesis of colloidal gold nanoparticles in different solvents are studied. Especially under batch ablation conditions in highly viscous liquids with prolonged ablation times both shielding entities are closely interconnected and need to be disentangled. By performing liquid flow-assisted nanosecond laser ablation of gold in liquids with different viscosity and nanoparticle or bubble diffusivity, it is shown that a steady-state is reached after a few seconds with fixed individual contributions of bubble- and colloid-induced shielding effects. By analyzing dimensionless numbers (i.e., Axial Peclet, Reynolds, and Schmidt) it is demonstrated how these shielding effects strongly depend on the liquid’s transport properties and the flow-induced formation of an interface layer along the target surface. In highly viscous liquids, the transport of NPs and persistent bubbles within this interface layer is strongly diffusion-controlled. This diffusion-limitation not only affects the agglomeration of the NPs but also leads to high local densities of NPs and bubbles near the target surface, shielding up to 80% of the laser power. Hence, the ablation rate does not only depend on the total amount of shielding matter in the flow channel, but also on the location of the persistent bubbles and NPs. By comparing LAL in different liquids, it is demonstrated that 30 times more gas is produced per ablated amount of substance in acetone and ethylene glycol compared to ablation in water. This finding confirms that chemical effects contribute to the liquid’s decomposition and the ablation yield as well. Furthermore, it is shown that the highest ablation efficiencies and monodisperse qualities are achieved in liquids with the lowest viscosities and gas formation rates at the highest volumetric flow rates.

Programmable Random Lasing Pulses Based on Waveguide‐Assisted Random Scattering Feedback

AbstractProgrammable random lasing pulses are highly desired due to their promising applications in information security, flexible encoding systems, and smart imaging. However, the fixed random scattering configuration hinders their realization. Herein, a programmable random laser is designed to dynamically regulate random lasing pulses through introducing an external waveguide structure with random scattering feedback. Liquid and solid film random lasers are thus separately achieved. Most importantly, various pulse time series of random lasing can be flexibly realized by switching the adhesion/separation state between the gain and the destroyed waveguide structure. The Feinam coding system is further realized for encryption and information transmission by combining programmable random pulses. The results may widely expand the application prospects of random lasers in the fields of optical data recording, dynamic security labels, smart sensing, and flexible imaging.

Luminescence features of mononuclear Sm(III) complexes with heterocyclic ligands

Three ternary luminescent Sm(III) complexes were synthesized using 4-oxo-4H-1-benzopyran-3-carboxaldehyde (L), 4-Methyl-1,10-Phenanthroline (mphen), 2,2′-Biquinoline (biq), and Bathocuproine (bathocup) organic ligands. The synthesized materials were thoroughly characterized by ESI-MS+, CHN elemental analysis, Thermogravimetric analysis, UV–vis spectroscopy, FTIR, PXRD, FESEM, and PL spectroscopy techniques. The existence of sharp-narrow peaks in X-ray diffractogram confirmed crystallinity in the complexes. The ESI-MS+ and CHN data were in accordance with the proposed molecular formula of prepared materials. The optical bandgap (Eg) assessed from the Tauc plots suggested the direct electronic transition and semi-conducting character of the complexes with bandgap falling in the range 2.86–2.93 eV. The room temperature luminescence studies, carried out in the solution and powder state displayed three noticeable peaks from excited (4G5/2) to ground state (6H5/2, 7/2, 9/2) at ∼566, 601, and 647 nm, under UV excitation. The orange-red emission by the complexes was also confirmed through CIE chromaticity. The complexes possess good thermal stability. The prepared complexes might be potential candidate for liquid lasers, bio-assays, and solid-state lighting applications.

Liquid crystal tunable vertical cavity surface emission laser with inner cavity sub-wavelength grating

With the rapid development of information technology, a wavelength-tunable vertical cavity surface emitting laser (VCSEL) is urgently needed as an optical signal source in dense wavelength division multiplexing (DWDM). Liquid crystal tunable VCSEL realized by utilizing the birefringence characteristics of liquid crystal has the advantages of stable polarization, high reliability, continuous wavelength tuning. In this paper, a liquid crystal tunable VCSEL structure based on intracavity sub wavelength grating is designed, and the influence of liquid crystal layer and sub wavelength grating on the wavelength tuning characteristics of VCSEL are analyzed and studied in depth. The results show that the thickness of the liquid crystal layer in the tunable VCSEL structure not only affects the wavelength tuning range, but also determines the mode hopping in the tuning process. In addition, an effective refractive index antireflection layer is formed by designing the subwavelength grating structure, and the refractive index difference between the liquid crystal layer and the semiconductor layer is optimized to further improve the wavelength tuning range and tuning efficiency. When the center wavelength is 980 nm, the tuning range is increased by 42%, reaching 41 nm, and the wavelength tuning efficiency is increased by 41%. It provides a new method of designing the VCSEL laser with high beam quality and continuous wavelength tuning.

Экспериментальное и теоретическое исследование спектроскопии биядерных борфторидных комплексов дипиррометенов

The spectroscopic characteristics of mono and binuclear boron fluoride complexes of dipyrromethenes in various solvents and solid-state polymer media (films) are investigated depending on the wavelength and intensity of the exciting radiation. Along with experimental studies, quantum-chemical calculations of the electronic structure and geometry of electronically excited molecules were carried out, an interpretation of the experimental data (absorption and emission bands) was given, and a connection between the absorption spectra and the structure of bis (dipyrromethenes) and their conformations was established. The analysis of the obtained results is carried out in comparison with the modern literature data. The possibilities of practical application of the studied compounds in the development of liquid and solid-state lasers and optical solvent polarity sensor are discussed.

Liquid Crystal Random Laser: Principles and Research Progresses

Liquid Crystal Random Laser: Principles and Research Progresses

Studies on surface morphology of under liquid laser ablated magnesium alloy

The magnesium-based alloys have limited wear resistance and tribological properties and tend to lose their functionality prematurely under sliding conditions. This can be addressed through conventional surface treatment and coatings. The surface texturing and coating can be simultaneously achieved by carrying out laser ablation under liquid medium. This improves the lubricant film, the unwanted thermal cracking, vaporization of metal and metallurgical changes. In this experimental investigation, the disintegrated melt deposition (DMD) processed Mg3Al alloy was subjected to under liquid laser ablation in 1 proponal containing graphite particles of size range 5–9 μm stirred at 1900 rpm by a magnetic stirrer. The under liquid laser ablation yielded nanostructured surface with grooves and islands that promote wettability and the presence of graphite ensuring an improvement of tribological properties. In this study, a 60 W power Nd YAG fiber laser was used to etch the surface and achieve the under liquid ablation. The surface roughness and morphology were studied using Atomic Force Microscopy and the chemical analysis of the laser-treated surface was done using Raman spectroscopy.

Airborne collimator display with liquid crystal imaging device and laser backlight system

Airborne collimator display with liquid crystal imaging device and laser backlight system