scholarly journals Micropatterning MoS2/Polyamide Electrospun Nanofibrous Membranes Using Femtosecond Laser Pulses

Photonics ◽  
2019 ◽  
Vol 6 (1) ◽  
pp. 3 ◽  
Author(s):  
Kelly T. Paula ◽  
Luiza A. Mercante ◽  
Rodrigo Schneider ◽  
Daniel S. Correa ◽  
Cleber R. Mendonca
Keyword(s):  
Laser Ablation ◽  
Composite Nanofibers ◽  
Electrospun Nanofibers ◽  
Scanning Speed ◽  
Laser Pulses ◽  
Femtosecond Laser Pulses ◽  
Spectroscopic Techniques ◽  
Fs Laser ◽  
Nanofibrous Membranes ◽  
Scale Control

The capability of modifying and patterning the surface of polymer and composite materials is of high significance for various biomedical and electronics applications. For example, the use of femtosecond (fs) laser ablation for micropatterning electrospun nanofiber scaffolds can be successfully employed to fabricate complex polymeric biomedical devices, including scaffolds. Here we investigated fs-laser ablation as a flexible and convenient method for micropatterning polyamide (PA6) electrospun nanofibers that were modified with molybdenum disulfide (MoS2). We studied the influence of the laser pulse energy and scanning speed on the topography of electrospun composite nanofibers, as well as the irradiated areas via scanning electron microscopy and spectroscopic techniques. The results showed that using the optimal fs-laser parameters, micropores were formed on the electrospun nanofibrous membranes with size scale control, while the nature of the nanofibers was preserved. MoS2-modified PA6 nanofibrous membranes showed good photoluminescence properties, even after fs-laser microstructuring. The results presented here demonstrated potential application in optoelectronic devices. In addition, the application of this technique has a great deal of potential in the biomedical field, such as in tissue engineering.

Fabrication and Characterization of Si Nano-Columns by Femtosecond Laser

2012 ◽  
Vol 16 ◽  
pp. 15-20 ◽  
Author(s):  
Omid Tayefeh Ghalehbeygi ◽  
Vural Kara ◽  
Levent Trabzon ◽  
Selcuk Akturk ◽  
Huseyin Kizil
Keyword(s):  
Laser Ablation ◽  
Femtosecond Laser ◽  
Laser Beam ◽  
Chemical Etching ◽  
Silicon Surface ◽  
Laser Pulses ◽  
Laser Beam Profile ◽  
Fs Laser ◽  
Fabrication And Characterization

We fabricated Si Nano-columns by a femtosecond laser with various wavelengths and process parameters, whilst the specimen was submerged in water. The experiments were carried out by three types of wavelengths i.e. 1030 nm, 515nm, 343nm, with 500 fs laser pulses. The scales of these spikes are much smaller than micro spikes that are constructed by laser irradiation of silicon surface in vacuum or gases like SF6, Cl2. The Si nano-columns of 300 nm or less in width were characterized by SEM measurements. The formation of these Si Nano-columns that were revealed by SEM observation, indicates chemical etching with laser ablation occurred when surface exposed by laser beam. We observed 200 nm spikes height at the center of laser beam profile and the ones uniform in height at lateral incident area.

scholarly journals Laser ablation of silicon with THz bursts of femtosecond pulses: an experimental and theoretical investigation

2021 ◽  
Author(s):  
Caterina Gaudiuso ◽  
Pavel N. Terekhin ◽  
Annalisa Volpe ◽  
Stefan Nolte ◽  
Bärbel Rethfeld ◽  
...  
Keyword(s):  
Laser Ablation ◽  
Thermal Load ◽  
Laser Pulses ◽  
Ablation Rate ◽  
Pulse Mode ◽  
Femtosecond Laser Pulses ◽  
Photon Absorption ◽  
Burst Frequency ◽  
Two Photon Absorption ◽  
Theoretical Investigations

Abstract In this work, we performed an experimental investigation supported by a theoretical analysis, to improve knowledge on the laser ablation of silicon with THz bursts of femtosecond laser pulses. Laser ablated craters have been created using 200 fs pulses at a wavelength of 1030 nm on silicon samples systematically varying the burst features and comparing to the Normal Pulse Mode (NPM). Using bursts in general allowed reducing the thermal load to the material, however, at the expense of the ablation rate. The higher the number of pulses in the bursts and the lower the intra-burst frequency, the lower is the specific ablation rate. However, bursts at 2 THz led to a higher specific ablation rate compared to NPM, in a narrow window of parameters. Theoretical investigations based on the numerical solution of the density-dependent two temperature model revealed that lower lattice temperatures are reached with more pulses and lower intra-burst frequencies, thus supporting the experimental evidence of the lower thermal load in Burst Mode (BM). This is ascribed to the weaker transient drop of reflectivity, which suggests that with bursts less energy is transferred from the laser to the material. This also explains the trends of the specific ablation rates. Moreover, we found that two-photon absorption plays a fundamental role during BM processing in the THz frequency range.

scholarly journals Femtosecond, picosecond, and nanosecond laser microablation: Laser plasma and crater investigation

2002 ◽  
Vol 20 (1) ◽  
pp. 67-72 ◽  
Author(s):  
A. SEMEROK ◽  
B. SALLÉ ◽  
J.-F. WAGNER ◽  
G. PETITE
Keyword(s):  
Laser Ablation ◽  
Theoretical Models ◽  
Laser Pulses ◽  
Femtosecond Laser Pulses ◽  
Laser Beams ◽  
Limiting Factors ◽  
Nanosecond Laser ◽  
Ablation Efficiency ◽  
Nanosecond Pulses ◽  
Focused Laser Beams

Crater shapes and plasma plume expansion in the interaction of sharply focused laser beams (10 μm waist diameter, 60 fs–6 ns pulse duration) with metals in air at atmospheric pressure were studied. Laser ablation efficiencies and rates of plasma expansion were determined. The best ablation efficiency was observed with femtosecond laser pulses. It was found that for nanosecond pulses, the laser beam absorption, its scattering, and its reflection in plasma were the limiting factors for efficient laser ablation and precise material sampling with sharply focused laser beams. The experimental results obtained were analyzed with relation to different theoretical models of laser ablation.

Ablation of Si and Ge Using UV Femtosecond Laser Pulses

1995 ◽  
Vol 397 ◽  
Author(s):  
G. Herbst ◽  
M. Steiner ◽  
G. Marowsky ◽  
E. Matthias
Keyword(s):  
Laser Ablation ◽  
Femtosecond Laser ◽  
Material Removal ◽  
Laser Pulses ◽  
Ablation Rate ◽  
Femtosecond Laser Pulses ◽  
Bond Breaking ◽  
Intensity Enhancement ◽  
Silicon And Germanium

ABSTRACTLaser ablation of silicon and germanium was carried out in moderate vacuum with l00fs to 400fs pulses at 248nm and intensities up to 3x1013 W/cm2. Evidence for non-thermal material removal was found. Imaged multishot ablation patterns display the intensity dependent self-structuring effect, forming well-known columnar structures. It is shown that continued irradiation of these structures eventually results in comparatively clean ablation. An increase of ablation rate with depth was observed. The reason is an intensity enhancement inside the pits by reflective focussing to a level where bond-breaking takes place. Furthermore, it was noticed that ablation contours can be significantly improved by electrically grounding the target.

Femtosecond Laser Ablation of Zr55Al10Ni5Cu30 Bulk Metallic Glass

2007 ◽  
Vol 539-543 ◽  
pp. 1951-1954 ◽  
Author(s):  
Tomokazu Sano ◽  
Kengo Takahashi ◽  
Akio Hirose ◽  
Kojiro F. Kobayashi
Keyword(s):  
Laser Ablation ◽  
Metallic Glass ◽  
Femtosecond Laser ◽  
Bulk Metallic Glass ◽  
Pulse Energy ◽  
Femtosecond Laser Ablation ◽  
Laser Pulses ◽  
Femtosecond Laser Pulses ◽  
Ablation Depth ◽  
Polished Surface

Dependence of the femtosecond laser ablation depth on the laser pulse energy was investigated for Zr55Al10Ni5Cu30 bulk metallic glass. Investigation of the femtosecond laser ablation of bulk metallic glasses has not been reported. Femtosecond laser pulses (wavelength of 800 nm, pulse width of 100 fs, pulse energies of 2 – 900 μJ) were focused and irradiated on the polished surface of metals in air. The ablation depth of the metallic glass is deeper than that of its crystallized metal at a pulse energy in the strong ablation region. We suggest that the energy loss at grain boundaries of hot electrons which is accelerated by the laser electric field influence the ablation depth in the strong ablation region.

Nanoparticle Aluminum Preparation

2019 ◽  
Author(s):  
Soma Venugopal Rao ◽  
Krishnamurthi Muralidharan ◽  
Anuj A. Vargeese
Keyword(s):  
Laser Ablation ◽  
Femtosecond Laser ◽  
Energetic Materials ◽  
Laser Pulses ◽  
Femtosecond Laser Pulses ◽  
Aluminum Nanoparticles ◽  
Chemical Methods ◽  
Laser Ablation In Liquids ◽  
Recent Developments ◽  
Green Technique

An overview of recent developments in the synthesis of aluminum nanoparticles (Al NPs) and their applications in the field of energetic materials is presented. Various methods of preparing the Al NPs of different sizes including physical (laser ablation) and chemical methods are highlighted. Some of the results obtained by our group on the passivation of the Al NPs are highlighted. The laser ablation in liquids technique with ultrashort (picosecond and femtosecond) laser pulses is a green technique for preparing Al NPs devoid of any precursors, whereas the chemicals method yields passivated Al NPs. Among the various applications of the Al NPs, energetic applications are discussed in detail. This article is concluded by emphasizing the prospects of Al NPs in various energetic applications and the future of different techniques to synthesize them.

scholarly journals Femtosecond laser ablation of brass: A study of surface morphology and ablation rate

2012 ◽  
Vol 30 (3) ◽  
pp. 473-479 ◽  
Author(s):  
Mohamed E. Shaheen ◽  
Brian J. Fryer
Keyword(s):  
Laser Ablation ◽  
Femtosecond Laser ◽  
Surface Morphology ◽  
Fine Particles ◽  
Femtosecond Laser Ablation ◽  
Laser Pulses ◽  
Ambient Air ◽  
Ablation Rate ◽  
Femtosecond Laser Pulses ◽  
Nanosecond Laser

AbstractThe interaction of near infrared femtosecond laser pulses with a Cu based alloy (brass) in ambient air at atmospheric pressure and under different laser conditions was investigated. The effects of laser fluence and number of pulses on surface morphology and ablation rate were studied using scanning electron microscopy (SEM) and optical microscopy. Ablation rates were found to rapidly increase from 83 to 604 nm/pulse in the fluence range 1.14–12.21 J/cm2. At fluence >12.21 J/cm2, ablation rates increased slowly to a maximum (607 nm/pulse at 19.14 J/cm2), and then decreased at fluence higher than 20.47 J/cm2 to 564 nm/pulse at 24.89 J/cm2. Large amounts of ablated material in a form of agglomerated fine particles were observed around the ablation craters as the number of laser pulses and fluence increased. The study of surface morphology shows reduced thermal effects with femtosecond laser ablation in comparison to nanosecond laser ablation at low fluence.

Laser Ablation Synthesis in Solution of Nanoantimicrobials for Food Packaging Applications

2015 ◽  
Vol 1804 ◽  
pp. 37-42 ◽  
Author(s):  
Maria C. Sportelli ◽  
Antonio Ancona ◽  
Rosaria A. Picca ◽  
Adriana Trapani ◽  
Annalisa Volpe ◽  
...  
Keyword(s):  
Laser Ablation ◽  
Metal Ion ◽  
Food Packaging ◽  
Antimicrobial Properties ◽  
Laser Pulses ◽  
Femtosecond Laser Pulses ◽  
Ion Release ◽  
Bioactive Materials ◽  
Molar Ratios ◽  
Metal Ion Release

ABSTRACTDesigning bioactive materials, with controlled metal ion release, exerting significant bioactivity and associated low toxicity for humans, is nowadays one of the most important challenges for the scientific community. In this work, we propose a new material combining the well-known antimicrobial properties of copper nanoparticles (CuNPs) with those of bioactive chitosan (CS), a cheap natural polymer widely exploited for its biodegradability and nontoxicity. Here, we used ultrafast femtosecond laser pulses to finely fragment, via laser ablation, a Cu solid target immersed into aqueous CS solutions. Homogeneously dispersed copper-chitosan (Cu-CS) colloids were obtained by tuning the Cu/CS molar ratios, according to the initial chitosan concentration, as well as other experimental parameters. Cu-CS colloids were characterized by several techniques, like UV-Vis and X-ray Photoelectron spectroscopies (XPS). Transmission Electron Microscopy (TEM) was used to morphologically characterize the novel nanocomposites.

Structural changes in GaAs induced by ultrafast (fs) laser pulses

1998 ◽  
Vol 13 (7) ◽  
pp. 1808-1811 ◽  
Author(s):  
L. Nánai ◽  
R. Vajtai ◽  
Cs. Beleznai ◽  
J. Remes ◽  
S. Leppävuori ◽  
...  
Keyword(s):  
Structural Changes ◽  
Microprobe Analysis ◽  
Laser Pulses ◽  
Femtosecond Laser Pulses ◽  
Electron Hole ◽  
Zinc Blend ◽  
Force Microscopy ◽  
Atomic Force ◽  
Electron Hole Plasma ◽  
Fs Laser

Ultrafast changes in the crystal structure of GaAs induced by intense femtosecond laser pulses are detected and investigated. Atomic force microscopy and Raman microprobe analysis of the laser-treated area show centrosymmetric (disordered) features which are different from the original zinc-blend structure of the GaAs lattice. The frozen-in structure shows evidence for a special heat transfer from the laser-induced crater to the boundary, namely the heat has been transferred ballistically by a high-density electron-hole plasma.

Modeling of Moving Breakdown by Femtosecond Laser Pulses in Dielectrics

2000 ◽  
Author(s):  
C. H. Fan ◽  
J. P. Longtin
Keyword(s):  
Laser Ablation ◽  
Pulse Propagation ◽  
Focal Point ◽  
Large Fraction ◽  
Laser Pulses ◽  
Femtosecond Laser Pulses ◽  
Shielding Effectiveness ◽  
Beam Path ◽  
Breakdown Region ◽  
Breakdown Model

Abstract Laser ablation is becoming increasingly important in the fields of micromaching, thin film formation, and bioengineering applications. In laser ablation, the ablation rates and feature quality strongly depend on the size of the breakdown region in the material. This region is characterized by a high density of free electrons, which absorb a large fraction of energy from the laser pulse that results in material vaporization in solids or liquids. For nanosecond- and picosecond pulses, the breakdown region tends to form near the beam focus and then expand back along the beam path toward the laser; this phenomenon is called moving breakdown. For femtosecond pulses, however, breakdown begins up the beam path and then propagates toward the focal point. A moving breakdown model presented by Docchio et al. (1988a) successfully explains and predicts the time-dependent breakdown region in the nanosecond regime, however it does not adequately describe propagation of the breakdown region at pico- and femtosecond time scales. In the present work, a modified moving breakdown model is proposed that includes the pulse propagation and small spatial extent of ultrafast laser pulses. This revised model shows that pulse propagation becomes significant for pulsewidths less than 10 picoseconds. The new model characterizes the pulse behavior as it interacts with a material within the focal volume in both solids and liquids. The model may also be useful in estimating the time- and space-resolved electron density in the interaction volume, the breakdown threshold of a material, shielding effectiveness, energy deposition, and the temperature increase in the material.

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