Time dependence of the laser-induced femtosecond lattice instability of Si and GaAs: Role of longitudinal optical distortions

Stampfli, P.

doi:10.1103/physrevb.49.7299

Cited by 226 publications

(144 citation statements)

References 27 publications

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“…Silicon is a widely studied material in the context of strongly driven phase transitions, both experimentally [1][2][3][4][5][6] and theoretically [13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29], where it is found to melt on a subpicosecond timescale at high excitations. Most theoretical studies of nonthermal melting in silicon have employed ab initio simulation methods.…”

Section: Introductionmentioning

confidence: 99%

Simulating electronically driven structural changes in silicon with two-temperature molecular dynamics

Darkins

Murphy

et al. 2018

Phys. Rev. B

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Radiation can drive the electrons in a material out of thermal equilibrium with the nuclei, producing hot, transient electronic states that modify the interatomic potential energy surface. We present a rigorous formulation of two-temperature molecular dynamics that can accommodate these electronic effects in the form of electronic-temperature-dependent force fields. Such a force field is presented for silicon, which has been constructed to reproduce the ab initio-derived thermodynamics of the diamond phase for electronic temperatures up to 2.5 eV, as well as the structural dynamics observed experimentally under nonequilibrium conditions in the femtosecond regime. This includes nonthermal melting on a subpicosecond timescale to a liquidlike state for electronic temperatures above ∼1 eV. The methods presented in this paper lay a rigorous foundation for the large-scale atomistic modeling of electronically driven structural dynamics with potential applications spanning the entire domain of radiation damage.

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Section: Introductionmentioning

confidence: 99%

Simulating electronically driven structural changes in silicon with two-temperature molecular dynamics

Darkins

Murphy

et al. 2018

Phys. Rev. B

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“…Similar behavior has been observed in the case of femtosecond optical excitation 6,7 and attributed to nonthermal melting. 8 Although the temporal resolution in the experiment discussed here was limited by the probe pulse duration to 10 ps, the observed increase of the reflectivity most likely occurs on subpicosecond time scales and is similarly related to an electronically induced phase transition.…”

mentioning

confidence: 99%

Ablation of solids using a femtosecond extreme ultraviolet free electron laser

Stojanović

Linde

Sokolowski‐Tinten

et al. 2006

Applied Physics Letters

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The ablation of solids by high energy femtosecond pulses from an extreme ultraviolet ͑XUV͒ free electron laser has been investigated using picosecond optical imaging. The time-resolved measurements are supplemented by an analysis of the permanent structural surface modifications. Compared with femtosecond optical excitation, distinct differences in the material response are found which are attributed to the increased penetration depth of the XUV radiation and the absence of any absorption nonlinearities. © 2006 American Institute of Physics. ͓DOI: 10.1063/1.2405398͔ Ultrashort laser pulses allow to create states of strong electronic excitation and high temperature and pressure in solid materials. Under these conditions phase transitions and ablation occur on very rapid time scales, and often along unusual, nonequilibrium pathways. Up to now mainly femtosecond optical lasers have been used for material excitation, but the interpretation of experimental data is often difficult because of the highly nonlinear nature of the deposition of optical energy in the intensity range of interest ͑Ͼ10 12 W/cm 2 ͒.Unique possibilities for both generating and probing high energy density states of matter are emerging with the recent advent of short-wavelength accelerator-based light sources. 1,2 Among these future light sources the extreme ultraviolet ͑XUV͒ free electron laser ͑FEL͒ FLASH ͑free electron laser in Hamburg͒ 3 at the Deutsches ElektronenSynchrotron ͑DESY͒ in Hamburg, Germany is currently the only self-amplified spontaneous emission FEL 4 operating in the 6 -100 nm wavelength range.The irradiation of solid materials with such shortwavelength femtosecond pulses offers a number of advantages. First of all it permits a high degree of electronic excitation but with a strongly reduced influence of optical nonlinearities ͑i.e., multiphoton absorption and free carrier absorption͒. Moreover, for frequencies higher than the plasma frequency but lower than the frequency of the innershell absorption edge, the absorption depth for some materials can be rather long. Therefore, ultrashort XUV pulses allow the preparation of rather well-defined excitation conditions in relatively large sample volumes as compared with femtosecond optical pulses.In this letter we report on the results of experiments performed at FLASH on the interaction of ultrashort high intensity ͑10 12 -10 14 W/cm 2 ͒ XUV pulses with solid surfaces. In an XUV-pump/optical probe experiment picosecond optical imaging has been used to follow the dynamics of short-pulse XUV-induced phase transitions and ablation. The time-resolved measurements are supplemented by a characterization of the permanent structural modifications of the irradiated surfaces. A comparison with femtosecond optical excitation reveals distinct differences in the material response which we attribute to the absence of absorption nonlinearities and the increased penetration of the XUV light in the materials ͑Si and GaAs͒ discussed in this study.Experiments were performed at beamline BL2 of the FLASH...

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“…This is sometimes referred to as non-thermal melting. Already 20 years ago it was found that the optical properties of the surface change from that of a solid to that of the liquid in a few 100 fs [36]. In a pioneering study by Rousse et al [1] the lattice disordering was directly measured to atomic pathways have not been possible to deduce in this and subsequent studies using laser-produced plasma sources.…”

Section: Non-thermal Melting Of Insbmentioning

confidence: 99%