Computational and experimental study of the cluster size distribution in MAPLE

Leveugle, Elodie; Zhigilei, Leonid V.; Sellinger, Aaron T.; Fitzgerald, James W.

doi:10.1016/j.apsusc.2007.01.057

Cited by 45 publications

(25 citation statements)

References 7 publications

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“…Their UV-MAPLE experiments and molecular dynamics simulations suggested the formation of balloon-like structures with a polymer-rich shell and a matrix core resulting from internal boiling in polymer-matrix droplets. [159][160][161][162][163][164] Under conditions of sufficiently fast cooling enhanced by heat conduction to the substrate, surface patterns similar to those observed in Figure 15 were observed. However, direct comparison to RIR-MAPLE experiments would be misleading as UV lasers have much shorter optical penetration depths (tens of nm) and pulse durations (tens of ns), which result in much higher peak intensities.…”

Section: Discussionsupporting

confidence: 68%

Mechanisms of Resonant Infrared Matrix-Assisted Pulsed Laser Evaporation

Torres

Johnson

Haglund

et al. 2011

Critical Reviews in Solid State and Materials Sciences

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For the last decade, a variant of pulsed laser ablation, Resonant-Infrared Matrix-Assisted Pulsed Laser Evaporation (RIR-MAPLE), has been studied as a deposition technique for organic and polymeric materials. RIR-MAPLE minimizes photochemical damage from direct interaction with the intense laser beam by encapsulating the polymer in a high infrared-absorption solvent matrix. This review critically examines the thermally-induced ablation mechanisms resulting from irradiation of cryogenic solvent matrices by a tunable free electron laser (FEL). A semi-empirical model is used to calculate temperatures as a function of time in the focal volume and determine heating rates for different resonant modes in two model solvents, based on the thermodynamics and kinetics of the phase transitions induced in the solvent matrices.Three principal ablation mechanisms are discussed, namely normal vaporization at the surface, normal boiling, and phase explosion. Normal vaporization is a highly inefficient polymer deposition mechanism as it relies on collective collisions with evaporating solvent molecules. Diffusion length calculations for heterogeneously nucleated vapor bubbles show that normal boiling is kinetically limited. During high-power pulsed-FEL irradiation, phase explosion is shown to be the most significant contribution to polymer deposition in RIR-MAPLE. Phase explosion occurs when the target is rapidly heated (10 8 to 10 10 K/s) and the solvent matrix approaches its critical temperature. Spontaneous density stratification (spinodal decay) within the condensed metastable phase leads to rapid homogeneous nucleation of vapor bubbles. As these vapor bubbles interconnect, large pressures build up within the condensed phase, leading to target explosions and recoil-induced ejections of polymer to a near substrate. Phase explosion is a temperature (fluence) threshold-limited process, while surface evaporation can occur even at very low fluences.

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Section: Discussionsupporting

confidence: 68%

Mechanisms of Resonant Infrared Matrix-Assisted Pulsed Laser Evaporation

Torres

Johnson

Haglund

et al. 2011

Critical Reviews in Solid State and Materials Sciences

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“…9 of this book for a detailed discussion of MAPLE). Indeed, the ejection of the extended liquid structures observed in the simulations [113], can be related to "nanofiber" or "necklace" polymer surface features observed in SEM images of PMMA films deposited in MAPLE [124][125][126]182], as well as in films fabricated by ablation of a polymer target involving a partial thermal decomposition of the target material into volatile species [183]. Moreover, the effect of dynamic molecular redistribution in the ejected matrix-polymer droplets, leading to the generation of transient "molecular balloons" in which polymerrich surface layers enclose the volatile matrix material, has been identified in the simulations [114,126,184] as the mechanism responsible for the formation of characteristic wrinkled polymer structures observed experimentally in films deposited by MAPLE [114,126,182].…”

Section: Phase Explosion and Laser Ablationmentioning

confidence: 99%

“…3.2b, the "beads" representing the functional groups of a polymer molecule (monomers) are connected by anharmonic springs with strengths appropriate for chemical bonding. An example of the computational setup used in simulations of laser ablation of polymer solutions [113,124,125] is given in Fig. 3.2e.…”

Section: Coarse-grained MD Model For Simulation Of Laser Interactionsmentioning

confidence: 99%

“…In order to enable simulations of laser interaction with polymer solutions [107,113,114,[124][125][126], the breathing sphere model has recently been combined with the bead-and-spring model, commonly used in polymer modeling [127]. In the bead-and-spring model, schematically illustrated in Fig.…”

Section: Coarse-grained MD Model For Simulation Of Laser Interactionsmentioning

confidence: 99%

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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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“…Experimental observations of the existence of threshold fluence for the onset of the droplet ejection have been interpreted as evidence of the transition from thermal vaporization to phase explosion [31]. An important conclusion drawn from the simulations is that particles/droplets and small atomic/molecular clusters are unavoidable products of the processes of material ejection in the ablation regime [32].…”

Section: Ion and Atom Emissionmentioning

confidence: 96%

Laser Fabrication of Nanoparticles

Caricato

Luches

Martino

2015

Handbook of Nanoparticles

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Lasers are widely used for material processing (cutting, drilling, cleaning, film deposition, etc.). A recent application is for nanoparticle fabrication. Pulsed laser ablation is by far the fastest and clean method to fabricate nanoparticles directly from bulk targets. For this purpose, target ablation is performed in vacuum, in gas atmosphere, or in liquids with fast (nanosecond) and ultrafast (picosecond, femtosecond) laser pulses. Mostly metal but also semiconductor and ceramic nanoparticles were fabricated. In the early stage of this technique, the main problem was the large size distribution of the produced nanoparticles. But the possibility to independently handle laser pulse characteristics (wavelength, power density, pulse duration, etc.) and the accurate control and optimization of the ambient parameters is leading to an efficient tailoring of the nanoparticle size, due also to helpful theoretical and numerical models. A review is presented of the most important studies and of the obtained results.

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Computational and experimental study of the cluster size distribution in MAPLE

Cited by 45 publications

References 7 publications

Mechanisms of Resonant Infrared Matrix-Assisted Pulsed Laser Evaporation

Mechanisms of Resonant Infrared Matrix-Assisted Pulsed Laser Evaporation

Atomic/Molecular-Level Simulations of Laser–Materials Interactions

Laser Fabrication of Nanoparticles

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