Ultrafast thermal melting of laser-excited solids by homogeneous nucleation

Rethfeld, Baerbel; Sokolowski‐Tinten, K.; Linde, D. von der; Anisimov, S. I.

doi:10.1103/physrevb.65.092103

Cited by 226 publications

(170 citation statements)

References 35 publications

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“…This observation has been supported by the results of recent large-scale TTM-MD simulations aimed at establishing the maximum velocity of the melting front propagation in metals [152]. A surprising result from this study is that the maximum velocity of the melting front just below the limit of the crystal stability against homogeneous melting is below 3% of the speed of sound, more than an order of magnitude lower than commonly assumed in interpretation of the results of laser melting experiments, e.g., [10,14,153]. The relatively low maximum velocity of the melting front, revealed in the simulations, has direct implications for interpretation of the experimental data on the kinetics of melting.…”

Section: Mechanisms and Kinetics Of Laser Meltingsupporting

confidence: 62%

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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Section: Mechanisms and Kinetics Of Laser Meltingsupporting

confidence: 62%

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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“…High strain rates can turn the liquid region into an ensemble of droplets and ablation follows. This process is called the homogeneous nucleation 37 . Unfortunately, quantitative values on the formation and ejection of liquid droplets are difficult to access because the interfacial solid-liquid microscopic properties of the nucleation centers are not accurately known.…”

Section: Resultsmentioning

confidence: 99%

Hydrodynamic simulations of metal ablation by femtosecond laser irradiation

et al. 2005

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Ablation of Cu and Al targets has been performed with 170 fs laser pulses in the intensity range of 10 12 -10 14 W/cm 2 . We compare the measured removal depth with 1D hydrodynamic simulations. The electron-ion temperature decoupling is taken into account using the standard two-temperature model. The influence of the early heat transfer by electronic thermal conduction on hydrodynamic material expansion and mechanical behavior is investigated. A good agreement between experimental and numerical matter ablation rates shows the importance of including solid-to-vapor evolution of the metal in the current modeling of the laser matter interaction.

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“…Previously, the details of crystal melting and the temperature range over which solids may be superheated have been investigated. [1][2][3][4][5][6][7] In contrast to undercooling of liquid prior to crystallization, experimental superheating of crystals is difficult as grain boundaries and free surfaces lower the energy barriers for melt nucleation. 8,9 Special experimental designs 5 and rapid heating are required to superheat crystalline solids.…”

mentioning

confidence: 99%

“…8,9 Special experimental designs 5 and rapid heating are required to superheat crystalline solids. Catastrophic melting 1,2 and homogeneous nucleation 3,4 theories have been utilized to define the limits of superheating, and a wide range of superheating ( ϳ0.1-2.0) is predicted. Here, we will investigate the systematics of nucleation energy barrier for elements and compounds, and the corresponding superheating as a function of heating rate.…”

mentioning

confidence: 99%

Superheating systematics of crystalline solids

Luo

Ahrens

2003

Applied Physics Letters

112

107

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Systematics of superheating ( ϭT/T m Ϫ1) of crystalline solids as a function of heating rate (Q) are established as ␤ϭA(Q)( ϩ1) 2 , where the normalized energy barrier for homogeneous nucleation is ␤ϭ16 ␥ sl 3 /(3kT m ⌬H m 2 ), T is temperature, T m melting temperature, A a Q-dependent parameter, ␥ sl interfacial energy, ⌬H m heat of fusion, and k Boltzmann's constant. For all elements and compounds investigated, ␤ varies between 0.2 and 8. Superheating ( ϭT/T m Ϫ1) of a crystalline solid occurs when the long-range order of the crystalline structure is maintained up to certain temperature T above the equilibrium melting temperature T m . Previously, the details of crystal melting and the temperature range over which solids may be superheated have been investigated. [1][2][3][4][5][6][7] In contrast to undercooling of liquid prior to crystallization, experimental superheating of crystals is difficult as grain boundaries and free surfaces lower the energy barriers for melt nucleation. 8,9 Special experimental designs 5 and rapid heating are required to superheat crystalline solids. Catastrophic melting 1,2 and homogeneous nucleation 3,4 theories have been utilized to define the limits of superheating, and a wide range of superheating ( ϳ0.1-2.0) is predicted. Here, we will investigate the systematics of nucleation energy barrier for elements and compounds, and the corresponding superheating as a function of heating rate. We also compare theory to superheating achieved in experiments and simulations.Homogeneous nucleation of melt may be described via classical theories. 9-14 Let I be the rate per unit volume of steady-state homogeneous nucleation of melt in solid: 14,15 IϭI 0 exp ͩ Ϫ ⌬G c kT ͪ , ͑1͒where ⌬G c is the critical Gibbs free energy for nucleation, and k is Boltzmann's constant. then I can be written as IϭI 0 f (␤, ), withNucleation rate I is controlled by f (␤, ), essentially by ␤ at a given temperature. Equations ͑1͒-͑3͒ are also applicable to the undercooling case.To estimate the magnitude of ␤, we note that ␥ sl ϳ0.1 J/m 2 , T m ϳ10 3 K and ⌬H m ϳ10 9 J/m 3 , yields ␤ ϳ1.2. Based on previous data, 14 ␤ for elements is calculated ͑Fig. 1͒. For Group IVB-IIB elements, ␤ is 0.9-3.1, except for Hg ͑6.3͒. For most transition metals, ␤ϳ1.8. Due to the unproportionally lower ⌬H m and T m , Group IIIA-VIA elements have larger ␤ values ͑2.5-8.2͒ except Al ͑1.5͒ and Se ͑0.2͒. Figure 1 demonstrates the periodic nature of ␤ for elements due to their periodic variations in electronic structure, with peaks occurring mostly at Group IIIA-VIA elements and Hg. ␤ for compounds such as some alkali halides and silicates is similar. In general, ␥ sl increases with T m and ⌬H m , because ␥ sl , T m , and ⌬H m are fundamentally related to binding energy. Thus, although ␤ is sensitive to ␥ sl , varia-

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Ultrafast thermal melting of laser-excited solids by homogeneous nucleation

Cited by 226 publications

References 35 publications

Atomic/Molecular-Level Simulations of Laser–Materials Interactions

Atomic/Molecular-Level Simulations of Laser–Materials Interactions

Hydrodynamic simulations of metal ablation by femtosecond laser irradiation

Superheating systematics of crystalline solids

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