Investigation of nanoparticle generation during femtosecond laser ablation of metals

Noël, Sylvie; Hermann, J.; Itina, Tatiana E.

doi:10.1016/j.apsusc.2007.01.081

Cited by 162 publications

(72 citation statements)

References 19 publications

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“…An opposite trend, however, is reported for Cu and Au, 80,81 where a large fraction of the ablated material is atomized at low fluences and the transition to the high-fluence regime corresponds to an increase in the efficiency of nanoparticle generation. The contradictory experimental results suggest the need for further investigation of the material-dependent characteristics of the ablation process.…”

Section: From Melting To Spallation and Phase Explosionmentioning

confidence: 87%

Atomistic Modeling of Short Pulse Laser Ablation of Metals: Connections between Melting, Spallation, and Phase Explosion

2009

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The mechanisms of short pulse laser interactions with a metal target are investigated in simulations performed with a model combining the molecular dynamics method with a continuum description of laser excitation, electron-phonon equilibration, and electron heat conduction. Three regimes of material response to laser irradiation are identified in simulations performed with a 1 ps laser pulse, which corresponds to the condition of stress confinement: melting and resolidification of a surface region of the target, photomechanical spallation of a single or multiple layers or droplets, and an explosive disintegration of an overheated surface layer (phase explosion). The processes of laser melting, spallation, and phase explosion are taking place on the same time scale and are closely intertwined with each other. The transition to the spallation regime results in a reduction of the melting zone and a sharp drop in the duration of the melting and resolidification cycle. The transition from spallation to phase explosion is signified by an abrupt change in the composition of the ejected plume (from liquid layers and/or large droplets to a mixture of vapor-phase atoms, small clusters and droplets), and results in a substantial increase in the duration of the melting process. In simulations performed with longer, 50 ps, laser pulses, when the condition for stress confinement is not satisfied, the spallation regime is absent and phase explosion results in smaller values of the ablation yield and larger fractions of the vapor phase in the ejected plume as compared to the results obtained with a 1 ps pulse. The more vigorous material ejection and higher ablation yields, observed in the simulations performed with the shorter laser pulse, are explained by the synergistic contribution of the laser-induced stresses and the explosive release of vapor in phase explosion occurring under the condition of stress confinement.

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Section: From Melting To Spallation and Phase Explosionmentioning

confidence: 87%

Atomistic Modeling of Short Pulse Laser Ablation of Metals: Connections between Melting, Spallation, and Phase Explosion

2009

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“…In particular, a detailed analysis of the dynamics of the plume formation in simulations performed for molecular targets with both long (no stress confinement) [110] and short (stress confinement) [185] laser pulses and fluences about twice the threshold for the ablation onset, reveals that only small clusters and monomers are ejected at the front of the expanding plume, medium-sized clusters are localized in the middle of the expanding plume, whereas the larger liquid droplets formed later during the plume development tend to be slower and are closer to the original surface. The cluster segregation effect, predicted in the simulations, can be related to the recent results of plume imaging experiments [186][187][188][189][190], where splitting of the plume into a fast component with optical emission characteristic for neutral atoms and a slow component with blackbody-like emission attributed to the presence of hot clusters [191], is observed. Similarly, and consistently with the results of the simulations discussed in [110,185], a layered structure of the plume (vaporized layer followed by small particles and larger droplets) observed in nanosecond laser ablation of water and soft tissue [192], is attributed to the succession of phase transitions occurring at different depths in the irradiated target [192,193].…”

Section: Phase Explosion and Laser Ablationmentioning

confidence: 99%

Atomic/Molecular-Level Simulations of Laser–Materials Interactions

Zhigilei

Lin

Ivanov

et al. 2009

Laser-Surface Interactions for New Materials Production

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Summary. Molecular/atomic-level computer modeling of laser-materials interactions is playing an increasingly important role in the investigation of complex and highly nonequilibrium processes involved in short-pulse laser processing and surface modification. This chapter provides an overview of recent progress in the development of computational methods for simulation of laser interactions with organic materials and metals. The capabilities, advantages, and limitations of the molecular dynamics simulation technique are discussed and illustrated by representative examples. The results obtained in the investigations of the laser-induced generation and accumulation of crystal defects, mechanisms of laser melting, photomechanical effects and spallation, as well as phase explosion and massive material removal from the target (ablation) are outlined and related to the irradiation conditions and properties of the target material. The implications of the computational predictions for practical applications, as well as for the theoretical description of the laser-induced processes are discussed. IntroductionShort-pulse lasers are used in a diverse range of applications, from advanced materials processing, cutting, drilling, and surface micro-and nanostructuring [1,2] to pulsed-laser deposition of thin films and coatings [3], laser surgery [4,5], and artwork restoration [6,7], and to the exploration of the conditions for inertial confinement fusion, with the world's most energetic laser system being built at the National Ignition Facility at Lawrence Livermore National Laboratory [8]. At the fundamental science level, short-pulse laser irradiation has the ability to bring material into a highly nonequilibrium state and provides a unique opportunity to probe the material behavior under extreme conditions. In particular, optical pump-probe experiments have been used to investigate transient changes in the electronic structure of the irradiated surface with high (often subpicosecond) temporal resolution [9][10][11][12][13], whereas recent advances in time-resolved X-ray and electron diffraction

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“…Molecular dynamics (MD) method [15]- [20] directly simulates molecular movement and interactions and can be used to investigate the evaporation process or to study the formation and evolution processes of clusters of many materials [13], [16], [21]- [23]. Several MD simulations [24], [25] and experiments [26]- [28] of laser ablation solids shown, that clusters are observed in the expanding plume of ablation. To describe clusters formation in the laser ablation process, a combination of the MD technique and the direct simulation Monte Carlo (DSMC) method [29] is developed [14], [28], [30]- [33].…”

Section: Introductionmentioning

confidence: 99%

Formation of nanoparticles by short and ultra-short laser pulses

Gouriet

Itina

Noël

et al. 2008

High-Power Laser Ablation VII

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The main objective of this study is to explain the experimental observations. To simulate material ablation, plume formation and its evolution, we developed a combined molecular dynamics (MD) and direct simulation Monte Carlo (DSMC) computational study of laser ablation plume evolution. The first process of the material ablation is described by the MD method. The expansion of the ejected plume is modelled by the DSMC method. To better understand the formation and the evolution of nanoparticles present in the plume, we first used separate MD simulations to analyse the evolution of a cluster in the presence of background gas with different properties (density, temperature). In particular, we examine evaporation and growth reactions of a cluster with different size and initial temperature. As a result of MD calculations, we determinate the influence of the background gas parameters on the nanoparticles. The reactions rates such as evaporation/condensation, which are obtained by MD simulations, are directly transferred to the DSMC part of our combined model. Finally, several calculations performed by using MD-DSMC model demonstrate both plume dynamics and longer-time cluster evolution. Calculations results are compared with experimental findings.

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Investigation of nanoparticle generation during femtosecond laser ablation of metals

Cited by 162 publications

References 19 publications

Atomistic Modeling of Short Pulse Laser Ablation of Metals: Connections between Melting, Spallation, and Phase Explosion

Atomistic Modeling of Short Pulse Laser Ablation of Metals: Connections between Melting, Spallation, and Phase Explosion

Atomic/Molecular-Level Simulations of Laser–Materials Interactions

Formation of nanoparticles by short and ultra-short laser pulses

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