Identification of the main mixing process in the synthesis of alloy nanoparticles by laser ablation of compacted micropowder mixtures

AbstractAlloy nanoparticles offer the possibility to tune functional properties of nanoscale structures. Prominent examples of tuned properties are the local surface plasmon resonance for sensing applications and adsorption energies for applications in catalysis. Laser synthesis of colloidal nanoparticles is well suited for generating alloy nanoparticles of desired compositions. Not only bulk alloys but also compacted mixtures of single-metal micropowders can serve as ablation targets. However, it is still unknown how mixing of the individual metals transfers from the micro- to the nanoscale. This work experimentally contributes to the elucidation of the mixing processes during the laser-based synthesis of alloy nanoparticles. Key parameters, such as the initial state of mixing in the ablation target, the laser pulse duration, the laser spot size, and the ablation time, are varied. Experiments are performed on a cobalt-iron alloy, relevant for application in oxidation catalysis, in ethanol. The extent of mixing in the targets after ablation and in individual nanoparticles are studied by energy-dispersive X-ray spectroscopy and by cyclic voltammetry at relevant conditions for the oxygen evolution reaction, as model reaction. The results point at the benefits of well pre-mixed ablation targets and longer laser pulse durations for the laser-based synthesis of alloy nanoparticles. Graphical abstract

Download Full-text

Radial density profile and stability of capillary discharge plasma waveguides of lengths up to 40 cm

High Power Laser Science and Engineering ◽

10.1017/hpl.2021.6 ◽

2021 ◽

Vol 9 ◽

Author(s):

M. Turner ◽

A. J. Gonsalves ◽

S. S. Bulanov ◽

C. Benedetti ◽

N. A. Bobrova ◽

...

Keyword(s):

Laser Pulse ◽

Electron Density ◽

Density Profile ◽

Pulse Propagation ◽

Spot Size ◽

Capillary Discharge ◽

Electron Density Profile ◽

Plasma Waveguide ◽

Wakefield Acceleration ◽

Plasma Wakefield

Abstract We measured the parameter reproducibility and radial electron density profile of capillary discharge waveguides with diameters of 650 $\mathrm{\mu} \mathrm{m}$ to 2 mm and lengths of 9 to 40 cm. To the best of the authors’ knowledge, 40 cm is the longest discharge capillary plasma waveguide to date. This length is important for $\ge$ 10 GeV electron energy gain in a single laser-driven plasma wakefield acceleration stage. Evaluation of waveguide parameter variations showed that their focusing strength was stable and reproducible to $<0.2$ % and their average on-axis plasma electron density to $<1$ %. These variations explain only a small fraction of laser-driven plasma wakefield acceleration electron bunch variations observed in experiments to date. Measurements of laser pulse centroid oscillations revealed that the radial channel profile rises faster than parabolic and is in excellent agreement with magnetohydrodynamic simulation results. We show that the effects of non-parabolic contributions on Gaussian pulse propagation were negligible when the pulse was approximately matched to the channel. However, they affected pulse propagation for a non-matched configuration in which the waveguide was used as a plasma telescope to change the focused laser pulse spot size.

Download Full-text

Dependence of laser accelerated protons on laser energy following the interaction of defocused, intense laser pulses with ultra-thin targets

Laser and Particle Beams ◽

10.1017/s0263034611000395 ◽

2011 ◽

Vol 29 (3) ◽

pp. 345-351 ◽

Cited By ~ 22

Author(s):

C.M. Brenner ◽

J.S. Green ◽

A.P.L. Robinson ◽

D.C. Carroll ◽

B. Dromey ◽

...

Keyword(s):

Laser Pulse ◽

Focal Spot ◽

Laser Pulse Energy ◽

Laser Energy ◽

Spot Size ◽

Proton Flux ◽

Focal Spot Size ◽

Order Of Magnitude ◽

Laser Focal Spot ◽

Accelerated Protons

AbstractThe scaling of the flux and maximum energy of laser-driven sheath-accelerated protons has been investigated as a function of laser pulse energy in the range of 15–380 mJ at intensities of 1016–1018 W/cm2. The pulse duration and target thickness were fixed at 40 fs and 25 nm, respectively, while the laser focal spot size and drive energy were varied. Our results indicate that while the maximum proton energy is dependent on the laser energy and laser spot diameter, the proton flux is primarily related to the laser pulse energy under the conditions studied here. Our measurements show that increasing the laser energy by an order of magnitude results in a more than 500-fold increase in the observed proton flux. Whereas, an order of magnitude increase in the laser intensity generated by decreasing the laser focal spot size, at constant laser energy, gives rise to less than a tenfold increase in observed proton flux.

Download Full-text

A Comparative Study on the Oxidation of Label-Free Silver Triangular Nanoplates by Peroxides: Main Effects and Sensing Applications

Sensors ◽

10.3390/s20174832 ◽

2020 ◽

Vol 20 (17) ◽

pp. 4832

Author(s):

Aleksei Furletov ◽

Vladimir Apyari ◽

Alexey Garshev ◽

Stanislava Dmitrienko

Keyword(s):

Hydrogen Peroxide ◽

Spectral Characteristics ◽

Inorganic Ions ◽

Label Free ◽

Local Surface Plasmon Resonance ◽

Tert Butyl ◽

Sensing Applications ◽

Tert Butyl Hydroperoxide ◽

Resonance Band ◽

Butyl Peroxide

Nowadays, analytical systems based on silver triangular nanoplates (AgTNPs) have been shown as good prospects for chemical sensing. However, they still remain relatively poorly studied as colorimetric probes for sensing various classes of compounds. This study shows that these nanoparticles are capable of being oxidized by peroxides, including both hydrogen peroxide and its organic derivatives. The oxidation was found to result in a decrease in the AgTNPs’ local surface plasmon resonance band intensity at 620 nm. This was proposed for peroxide-sensitive spectrophotometric determination. Five peroxides differing in their structure and number of functional groups were tested. Three of them easily oxidized AgTNPs. The effects of a structure of analytes and main exterior factors on the oxidation are discussed. The detection limits of peroxides in the selected conditions increased in the series peracetic acid < hydrogen peroxide < tert-butyl hydroperoxide, coming to 0.08, 1.6 and 24 μmol L−1, respectively. tert-Butyl peroxybenzoate and di-tert-butyl peroxide were found to have no effect on the spectral characteristics of AgTNPs. By the example of hydrogen peroxide, it was found that the determination does not interfere with 100–4000-fold quantities of common inorganic ions. The proposed approach was successfully applied to the analysis of drugs, cosmetics and model mixtures.

Download Full-text

Nanosecond Laser Etching of Aluminum-Plated Composite Materials Applied to Frequency Selective Surfaces

Materials ◽

10.3390/ma13122808 ◽

2020 ◽

Vol 13 (12) ◽

pp. 2808

Author(s):

Jian Cheng ◽

Shufeng Jing ◽

Deyuan Lou ◽

Qibiao Yang ◽

Qing Tao ◽

...

Keyword(s):

Composite Materials ◽

Laser Pulse ◽

Focal Spot ◽

Incident Angle ◽

Spot Size ◽

Nanosecond Laser ◽

Frequency Selective Surfaces ◽

Laser Etching ◽

Focal Spot Size ◽

Frequency Selective

High-quality frequency selective surfaces (FSSs) are important for electromagnetic signal absorption/filtration. Usually, they are made from wave-transparent composite materials covered with a thin metal layer. Current machining methods show some disadvantages when performing fabrication on the structure. Based on its flexibility and uncontactable processing characteristics, nanosecond laser etching of aluminum-plated composite materials applied to FSSs was investigated. To observe the influence of the laser light incident angle, etching of a series of square areas with different incident angles was performed. Thereafter, an image processing method, named the image gray variance (IGV), was employed to perform etching quality evaluation analysis. The observed microscopic pictures of experimental samples were consistent with those of the IGV evaluation. The potential reasons that might affect the etching quality were analyzed. Following all the efforts above, an incident angle range of ±15° was recommended, and the best etching result was obtained at the incident angle of 10°. To observe the influence of the laser pulse overlap and focal spot size on the etched area border uniformity and on the potential damage to the base materials, a theoretical equation was given, and then its prediction of area border edge burrs fluctuation was compared with the experiments. Furthermore, SEM pictures of etched samples were examined. Based on the study, a processing window of the laser pulse overlap and focal spot size was recommended. To conclude, optimal etching results of the FSS materials could be guaranteed by using the right laser operating parameters with the nanosecond laser.

Download Full-text

Evaluation of SEE on a 32-bit Microprocessor by Laser Test and Heavy Ion Test

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.1105.391 ◽

2015 ◽

Vol 1105 ◽

pp. 391-396

Author(s):

Chun Qing Yu ◽

Long Fan ◽

Suge Yue ◽

Jian Hua Ma ◽

Hong Chao Zheng

Keyword(s):

Laser Pulse ◽

Low Cost ◽

Step Length ◽

Heavy Ion ◽

Spot Size ◽

Single Event ◽

Laser Spot Size ◽

Scanning Step ◽

Instruction Pipeline ◽

Made In

In this paper the SEE (single event effects) of different parts of device were explored on a 32-bit microprocessor with a five-stage instruction pipeline by laser test and heavy ion test. The cross section curves for different function units were obtained and the comparison of the dates obtained from laser test and heavy ion tests was made. In addition, laser test under different scanning steps were made which indicate that when the scanning step length is in small steps which is considerably equivalent to the laser spot size, there is little change in the number of single event errors caused by each laser pulse. Wherever with the scanning step increasing, the number of single event errors caused by each laser pulse will be reduced. Experiment results suggest that there are differences between laser test and the heavy ion test but have a similar trend. The pulsed laser is an extremely powerful and low-cost technique for SEE testing and will provide invaluable information in characterizing SEE in integrate circuits.

Download Full-text

Effect of obliquely external magnetic field on the intense laser pulse propagating in plasma medium

International Journal of Modern Physics B ◽

10.1142/s0217979220500447 ◽

2020 ◽

Vol 34 (07) ◽

pp. 2050044

Author(s):

Mehdi Abedi-Varaki

Keyword(s):

Magnetic Field ◽

External Magnetic Field ◽

Laser Pulse ◽

Magnetoactive Plasma ◽

Spot Size ◽

The Self ◽

Intense Laser ◽

Intense Laser Pulse ◽

Laser Spot Size ◽

Self Focusing

In this paper, self-focusing of intense laser pulse propagating along the obliquely external magnetic field on the collisional magnetoactive plasma by using the perturbation theory have been studied. The wave equation describing the interaction of intense laser pulse with collisional magnetoactive plasma is derived. In addition, employing source-dependent expansion (SDE) method, the analysis of the laser spot-size is discussed. It is shown that with increasing of the angle in obliquely external magnetic field, the spot-size of laser pulse decreases and as a result laser pulse becomes more focused. Furthermore, it is concluded that the self-focusing quality of the laser pulse has been enhanced due to the presence of obliquely external magnetic field in the collisional magnetoactive plasma. Besides, it is seen that with increasing of [Formula: see text], the laser spot-size reduces and subsequently the self-focusing of the laser pulse in plasma enhances. Moreover, it is found that changing the collision effect in the magnetoactive plasma leads to increases of self-focusing properties.

Download Full-text

Propagation of an ultrashort, high-intensity laser pulse in gas-target plasma

Journal of Plasma Physics ◽

10.1017/s0022377812000505 ◽

2012 ◽

Vol 78 (4) ◽

pp. 483-489 ◽

Cited By ~ 1

Author(s):

XIAOFANG WANG ◽

GUANGHUI WANG ◽

ZHANNAN MA ◽

KEGONG DONG ◽

BIN ZHU ◽

...

Keyword(s):

Laser Pulse ◽

High Intensity ◽

Spot Size ◽

High Energy ◽

Beam Radius ◽

Gas Target ◽

Target Plasma ◽

High Intensity Laser ◽

Gas Targets ◽

Intensity Laser

AbstractFor high-energy gain of electron acceleration by a laser wakefield, a stable or guiding propagation of an ultrashort, high-intensity laser pulse in a gas-target plasma is of fundamental importance. Preliminary experiments were carried out for the propagation of 30-fs, ~100-TW laser pulses of intensities ~1019W/cm2 in plasma of densities ~1019/cm3. Self-guiding length of nearly 1.4 mm was observed in a gas jet and 15 mm in a hydrogen-filled capillary. Fluid-dynamics simulations are used to characterize the two types of gas targets. Particle-in-cell simulations indicate that in the plasma, after the pulse's evolution of self-focusing and over-focusing, the high-intensity pulse could be stably guided with a beam radius close to the plasma wavelength. At lower plasma densities, a preformed plasma channel of a parabolic density profile matched to the laser spot size would be efficient for guiding the pulse.

Download Full-text

Platinum and platinum–iron alloy nanoparticles dispersed nitrogen-doped graphene as high performance room temperature hydrogen sensor

International Journal of Hydrogen Energy ◽

10.1016/j.ijhydene.2015.06.018 ◽

2015 ◽

Vol 40 (32) ◽

pp. 10346-10353 ◽

Cited By ~ 19

Author(s):

Raghu Sripada ◽

Vinayan Bhagavathi Parambath ◽

Mridula Baro ◽

Santhosh P Nagappan Nair ◽

Ramaprabhu Sundara

Keyword(s):

High Performance ◽

Room Temperature ◽

Iron Alloy ◽

Hydrogen Sensor ◽

Alloy Nanoparticles ◽

Nitrogen Doped ◽

Nitrogen Doped Graphene ◽

Doped Graphene

Download Full-text

Self focusing of a laser pulse in plasma with periodic density ripple

Laser and Particle Beams ◽

10.1017/s026303460900010x ◽

2009 ◽

Vol 27 (2) ◽

pp. 193-199 ◽

Cited By ~ 24

Author(s):

Sukhdeep Kaur ◽

A.K. Sharma

Keyword(s):

Laser Pulse ◽

Spot Size ◽

High Plasma ◽

The Self ◽

Intense Laser ◽

Wave Number ◽

Plasma Parameters ◽

Density Region ◽

Focusing Effect ◽

Self Focusing

AbstractPropagation of an intense laser pulse in plasma with a periodically modulated density is considered using envelope equations. The laser induces modifications of the plasma refractive indexviarelativistic and ponderomotive nonlinearities. In the region of high plasma density, the self focusing effect of nonlinearity suppresses the diffraction divergence, and the laser converges. As the beam enters into the low density region, the diffraction tends to diverge it offsetting the convergence due to the curvature it has acquired. For a given set of plasma parameters, there is a critical power of the laser above which it propagates in a periodically focused manner. Below this power the laser undergoes overall divergence. At substantially higher powers, the laser beam continues to converge until the saturation effect of nonlinearity suppresses the self focusing and diffraction predominates. The effect of density ripple is to cause overall increase in the self focusing length. The minimum spot size decreases with the wave number of the ripple.

Download Full-text