Time-Resolved Laser-Induced Phase Transformation in Aluminum

Williamson, S.; Mourou, G.; Li, J. C. M.

doi:10.1103/physrevlett.52.2364

Cited by 199 publications

(116 citation statements)

References 14 publications

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“…The electron pulses were generated by using a WilliamsonMourou streak camera arrangement (16) and an electron gun focusing system (17). Through the advancement of these generations of UED, we achieved in this laboratory 1-ps resolution in the development of ultrafast gas-phase electron diffraction (1).…”

Section: Ultrafast Electron Crystallography (Uec) Methodologymentioning

confidence: 99%

Ultrafast electron crystallography: Transient structures of molecules, surfaces, and phase transitions

Ruan

Vigliotti

Lobastov

et al. 2004

Proc. Natl. Acad. Sci. U.S.A.

119

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The static structure of macromolecular assemblies can be mapped out with atomic-scale resolution by using electron diffraction and microscopy of crystals. For transient nonequilibrium structures, which are critical to the understanding of dynamics and mechanisms, both spatial and temporal resolutions are required; the shortest scales of length (0.1-1 nm) and time (10 ؊13 to 10 ؊12 s) represent the quantum limit, the nonstatistical regime of rates. Here, we report the development of ultrafast electron crystallography for direct determination of structures with submonolayer sensitivity. In these experiments, we use crystalline silicon as a template for different adsorbates: hydrogen, chlorine, and trifluoroiodomethane. We observe the coherent restructuring of the surface layers with subangstrom displacement of atoms after the ultrafast heat impulse. This nonequilibrium dynamics, which is monitored in steps of 2 ps (total change <10 ps), contrasts that of the nanometer substrate. The effect of adsorbates and the phase transition at higher fluences were also studied through the evolution of streaks of interferences, Bragg spots (and their rocking curves), and rings in the diffraction patterns. We compare these results with kinematical theory and those of x-ray diffraction developed to study bulk behaviors. The sensitivity achieved here, with the 6 orders of magnitude larger cross section than x-ray diffraction, and with the capabilities of combined spatial (Ϸ0.01 Å) and temporal (300 -600 fs) resolutions, promise diverse applications for this ultrafast electron crystallography tabletop methodology.E lectron and x-ray diffraction, if endowed with ultrafast temporal resolution, can provide the ability of atomic-scale determination of structure and dynamics. In this laboratory, the method of choice has been ultrafast electron diffraction (UED) for many reasons; for recent review see ref. 1 and references therein. The extension of UED to the condensed phase and surface dynamics represents a major challenge, and here, we report on this development. With the combined spatial and temporal resolutions, it is possible to study macromolecular systems (2) and reach the nonstatistical regime of energy localization and rates (3). The sensitivity to surfaces, nanometer crystals, and adsorbates offers a unique feature for comparison with x-ray bulk studies (4-9).The conceptual framework of the approach is illustrated in Fig. 1. On the crystal, with or without the adsorbate (surface terminated by a monolayer of atoms or molecules), an ultrashort packet of electrons of 30 keV (de Broglie wavelength Ϸ0.07 Å), impinges with a wave vector k ជ i at a grazing incidence angle i Ͻ 5°. For elastic scattering, s ជ ϭ k ជ Ϫ k ជ i ; k ជ being the momentum of the scattered electron, s ϭ 4 ͞ ⅐sin ͞2, and is the scattering angle between k ជ and k ជ i . Because electrons interact strongly, the diffraction patterns give characteristics of the surface structure defined by the substrate and adsorbate. A change in temperature of the substrate is introd...

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Section: Ultrafast Electron Crystallography (Uec) Methodologymentioning

confidence: 99%

Ultrafast electron crystallography: Transient structures of molecules, surfaces, and phase transitions

Ruan

Vigliotti

Lobastov

et al. 2004

Proc. Natl. Acad. Sci. U.S.A.

119

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“…6,18 -25 Time-resolved electron diffraction and mass spectroscopy demonstrated the occurrence of superheating during intense laser irradiation. 7,26,27 In Table I In the previous discussion, we assumed I 0 is similar for undercooling and superheating cases. I 0 for undercooling could differ by several orders from that for superheating.…”

Section: ͑4͒mentioning

confidence: 99%

Superheating systematics of crystalline solids

Luo

Ahrens

2003

Applied Physics Letters

111

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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“…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 techniques [14][15][16][17][18][19][20][21][22] provide an opportunity to directly probe the ultrafast atomic dynamics in laser-induced structural transformations. Further optimization of experimental parameters in current applications, the emergence of new techniques, and interpretation of the results of probing the transient atomic dynamics in materials and at surfaces can be facilitated by computational modeling of laser-materials interactions.…”

Section: Introductionmentioning

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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Time-Resolved Laser-Induced Phase Transformation in Aluminum

Cited by 199 publications

References 14 publications

Ultrafast electron crystallography: Transient structures of molecules, surfaces, and phase transitions

Ultrafast electron crystallography: Transient structures of molecules, surfaces, and phase transitions

Superheating systematics of crystalline solids

Atomic/Molecular-Level Simulations of Laser–Materials Interactions

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