Fundamentals of femtosecond laser pulse and nanoparticles are analyzed by a two-temperature model. Ultrafast surface melting, surface nanoengineering and shock wave impact are evident in the surface of graphite by femtosecond irradiation. The interaction between femtosecond laser pulses and Au/Ag nanoparticles has been investigated. Two effects are identified at different intensities: photofrag...

Molecular dynamics of a short pulse laser irradiation of a molecular crystal are performed to investigate the dependence of the mechanism of ejection on laser ̄uence. We ®nd that at low laser ̄uences molecules are desorbed from a thin surface layer of solid sample. An increase in the laser ̄uence leads to the melting of the surface region and desorption occurs from an overheated melted state. A...

Excimer laser ablation of gold films deposited on a quartz crystal microbalance is investigated. The ablation rate is directly obtained from the frequency shift of the microbalance. The measured single-shot ablation rate is found to be at least two orders of magnitude higher than the numerical predictions based on a surface vaporization model. Surface morphologystudies indicate that hydrodynami...

OBJECTIVE The purpose of this study was to evaluate, by scanning electron microscopy (SEM), the effects of Nd:YAG laser irradiation applied perpendicular or parallel to the root canal dentin wall. METHODS Thirty human teeth were divided into two groups: Group A (20 roots), laser application with circular movements, parallel to the dentin root surface; and Group B (10 roots), roots cut longitu...

An AlCoCrCuFeNi high-entropy alloy (HEA) coating was fabricated on a pure magnesium substrate using a two-step method, involving plasma spray processing and laser re-melting. After laser re-melting, the microporosity present in the as-sprayed coating was eliminated, and a dense surface layer was obtained. The microstructure of the laser-remelted layer exhibits an epitaxial growth of columnar de...

introduction: the aim of this study was to investigate the morphological changes of human dentin after erbium-doped yttrium aluminum garnet (er:yag), carbon dioxide (co2) laser-irradiation and acid-etching by means of scanning electron microscopic (sem) m ethods: 9 extracted human third molars were used in this study. the teeth were divided in three groups: first group, co2 laser with power of ...

The threshold laser fluence for the onset of surface melting is calculated for Ni films of different thicknesses and for a bulk Ni target using a combined atomistic-continuum computational model. The model combines the classical molecular dynamics (MD) method for simulation of non-equilibrium processes of lattice superheating and fast phase transformations with a continuum description of the la...

Low surface quality of as-deposited laser metal deposition (LMD) parts is one the main drawbacks this additive manufacturing technology that prevents direct use without implementation costly and time consuming post-processes. An in-process finishing operation need auxiliary equipment highly appealing to overcome such issues. For reason, re-melting performed with same used for process a promisin...

The structural changes generated in surface regions of single crystal Ni targets by femtosecond laser irradiation are investigated experimentally and computationally for laser fluences that, in the multipulse irradiation regime, produce sub-100 nm high spatial frequency surface structures. Detailed experimental characterization of the irradiated targets combining electron back scattered diffrac...