The kinetics and microscopic mechanisms of laser melting and disintegration of thin Ni and Au films irradiated by a short, from 200 fs to 150 ps, laser pulse are investigated in a coupled atomistic-continuum computational model. The model provides a detailed atomic-level description of fast nonequilibrium processes of laser melting and film disintegration and, at the same time, ensures an adequ...

Time-resolved reflection high-energy electron diffraction has been developed to study the structure of surfaces. In this technique, an ultrafast laser pulse is split into two components. The first component interacts with the surface and serves as a transient heating source. The second component strikes the cathode of a photoactivated electron gun, photoelectrically producing pulses of electron...

This work investigates transport phenomena and mechanisms of droplet formation during a pulsed laser interaction with thin films. The surface of the target material is altered through material flow in the molten phase induced by a tightly focused laser energy flux. Such a process is useful for developing a laser-based micromachining technique. Experimental and numerical investigations of the la...

Studies of atomistic mechanisms, energetics and dynamics of surface and interfacial processes using computer-based molecular dynamics simulations employing realistic interaction potentials, open new avenues in investigations of basic and technological problems. Recent results of such studies are discussed for. surface processing via laser irradiation, superheating, melting, and annealing; stabi...

For biodegradable polymers such as poly (Llactic acid) (PLLA), material crystallinity has a considerable effect on degradation and physical properties. In this work, the effects of laser fluence of a 355 nm UV Q-switched Nd-YAG laser on the crystallinity and conformation at the surface of PLLA films and the factors affecting the transformation are investigated. Electron microscopy, X-ray diffra...

Optimization of processing parameters and exposure strategies is usually performed in additive manufacturing to set up the process; nevertheless, standards for roughness may not be evenly matched on a single complex part, since surface features depend on the building direction of the part. This paper aims to evaluate post processing treating via laser surface modification by means of scanning o...

Silicon nano-wires were fabricated using thin Silicon on Insulator (SOI) wafers and a combination of anisotropic wet etching by TetraMethyl Ammonium Hydroxide (TMAH) and Local Oxidation of Silicon (LOCOS). These nano-wires were submitted to laser exposure using gas immersion laser doping (GILD). The result was the formation of either periodic nano-structures or silicon balls. Since the process ...

The effects of melt-pool geometrical parameters on crystal growth and microstructure development during laser surface melting of single-crystal alloys were studied by means of mathematical modeling and experiments. A mathematical model was developed for the three-dimensional (3-D) melt-pool geometry and single-crystalline melt-pool solidification in laser surface melting. The 3-D meltpool geome...

The melting duration and molten depth are key information for Laser-Assisted Direct Imprinting, which raises the issue of the melting & solidification induced by excimer-pulse-laser shining through unilaterally transparent binary materials. Based on the matured laser-annealing analysis, the thermal-contact resistance is taken into account to simulate and predict the melting behavior for this pr...