Femtosecond laser-induced damage of gold films

Krüger, Jörg; Dufft, Daniela; Koter, R.; Hertwig, Andreas

doi:10.1016/j.apsusc.2007.02.164

Cited by 85 publications

(42 citation statements)

References 13 publications

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“…A notable observation from this simulation, however, is that the presence of sub-surface voids generated by the first laser pulse brings the absorbed fluence required for the material ejection below the single-pulse spallation threshold. This observation may be related to the incubation effect reported for multi-pulse irradiation of metal targets, when the laser fluence threshold for ablation/damage decreases with increasing number of laser pulses applied to the same area, e.g., [61,[65][66][67][68][69]. While the generation and accumulation of defects has been discussed in general terms as one of the mechanisms [12,[65][66][67]70] (along with the absorption enhancement due to roughening of the surface [61,68] and heat accumulation in high repetition rate irradiation [70]) responsible for the incubation effect, the current simulation results provide first direct insights into the laser-induced structural-modification processes that will also contribute to the reduction of the spallation threshold in the multi-pulse laser irradiation regime.…”

Section: Spallation By 2 Nd Pulse: Connection To Incubation Effectmentioning

confidence: 86%

Generation of subsurface voids and a nanocrystalline surface layer in femtosecond laser irradiation of a single-crystal Ag target

et al. 2015

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Structural transformations in a shallow surface region of a bulk Ag (001) target irradiated by a femtosecond laser pulse are investigated in large-scale atomistic simulations and experiments.The simulations reveal a complex interplay of fast laser melting, rapid resolidification, and the dynamic relaxation of laser-induced stresses that leads to the formation of a sub-surface porous region covered by a nanocrystalline surface layer. The generation of the porous region is consistent with the experimental observation of surface "swelling" occurring at laser fluences below the spallation/ablation threshold and may be related to the incubation effect in multi-pulse laser ablation of metals. The nanocrystalline layer is produced by massive nucleation of crystallites triggered by a deep undercooling of the melted surface region experiencing fast quenching at a rate on the order of 10 11 K/s. The predicted surface structure features random crystallographic orientation of nanograins and a high density of stacking faults, twins, and nanoscale twinned structural elements with five-fold symmetry, which suggests high hardness and possible enhancement of catalytic activity of the surface.

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Section: Spallation By 2 Nd Pulse: Connection To Incubation Effectmentioning

confidence: 86%

Generation of subsurface voids and a nanocrystalline surface layer in femtosecond laser irradiation of a single-crystal Ag target

et al. 2015

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“…The generation of crystal defects may be, thus, related to the incubation effect, when the laser fluence threshold for ablation/damage decreases significantly with increasing number of laser pulses applied to the same area, e.g., [145][146][147][148][149]. The high density of vacancies generated in the surface region should also play an important role in the redistribution of impurities or mixing/alloying in multicomponent or composite targets.…”

Section: Generation Of Crystal Defectsmentioning

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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“…Dielectric materials also have a much higher damage threshold than metals. For example a 1 ps, 800 nm pulse the multi-shot damage threshold of fused silica has been measured to be an incident fluence of 2-4 J/cm for gold [17]. This translates to a maximum surface field of 3.9 GV/m giving over an order of magnitude improvement compared to RF.…”

Section: List Of Figuresmentioning

confidence: 99%

Production, Characterization, and Acceleration of Optical Microbunches

Sears¹

2008

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Optical microbunches with a spacing of 800 nm have been produced for laser acceleration research. The microbunches are produced using a inverse Free-ElectronLaser (IFEL) followed by a dispersive chicane. The microbunched electron beam is characterized by coherent optical transition radiation (COTR) with good agreement to the analytic theory for bunch formation. In a second experiment the bunches are accelerated in a second stage to achieve for the first time direct net acceleration of electrons traveling in a vacuum with visible light.This dissertation presents the theory of microbunch formation and characterization of the microbunches. It also presents the design of the experimental hardware from magnetostatic and particle tracking simulations, to fabrication and measurement of the undulator and chicane magnets. Finally, the dissertation discusses three experiments aimed at demonstrating the IFEL interaction, microbunch production, and the net acceleration of the microbunched beam.At the close of the dissertation, a separate but related research effort on the tight focusing of electrons for coupling into optical scale, Photonic Bandgap, structures is presented. This includes the design and fabrication of a strong focusing permanent magnet quadrupole triplet and an outline of an initial experiment using the triplet to observe wakefields generated by an electron beam passing through an optical scale accelerator. Beyond the immediate influences on my career of those at SLAC and Stanford,

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Femtosecond laser-induced damage of gold films

Cited by 85 publications

References 13 publications

Generation of subsurface voids and a nanocrystalline surface layer in femtosecond laser irradiation of a single-crystal Ag target

Generation of subsurface voids and a nanocrystalline surface layer in femtosecond laser irradiation of a single-crystal Ag target

Atomic/Molecular-Level Simulations of Laser–Materials Interactions

Production, Characterization, and Acceleration of Optical Microbunches

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