Femtosecond phase-transition in hard x-ray excited bismuth

Makita, Mikako; Vartiainen, Ismo; Mohácsi, István; Caleman, Carl; Díaz, Ana; Jonsson, Hans; Juranić, Pavle; Medvedev, Nikita; Meents, A.; Mozzanica, A.; Opara, Nadia; Padeste, Celestino; Panneels, Valérie; Saxena, Vikrant; Sikorski, Marcin; Song, Sanghoon; Vera, Laura; Willmott, P. R.; Beaud, P.; Milne, Christopher J.; Ziaja, Beata; Dávid, Christian

doi:10.1038/s41598-018-36216-3

Cited by 10 publications

(5 citation statements)

References 36 publications

(81 reference statements)

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“…Detailed understanding of the mechanism for x-rayinduced atomic displacements is of great importance not only for confirming the validity of current serial femtosecond crystallography experiments, but for future realization of high-resolution structure analysis with intense XFEL pulses, such as visualizing charge-density distribution and chemical properties in matter at subatomic resolution (∼0.01 Å) [31]. A few pioneering groups attempted to follow x-ray-induced transient structural changes in various homoatomic materials (diamond [32,33], silicon [34,35], bismuth [36], and xenon clusters [37]) and in protein crystals [29] by using x-ray pump x-ray probe techniques. However, the initial disordering processes in these samples except for diamond [32,33] have not been fully revealed due to the insufficient temporal resolution.…”

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confidence: 99%

Delayed Onset and Directionality of X-Ray-Induced Atomic Displacements Observed on Subatomic Length Scales

et al. 2022

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confidence: 99%

Delayed Onset and Directionality of X-Ray-Induced Atomic Displacements Observed on Subatomic Length Scales

et al. 2022

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“…In particular, the way that NLTE dynamics simulations are fed by LTE IPD input such as EK and SP might be questionable for calculation of XFEL-created dense plasmas. Furthermore, nonthermal femtosecond phase transitions induced by an intense hard-x-ray pulse have been reported [51,52], thus necessitating an IPD treatment that is unrestricted, for both electrons and ions, by any thermal equilibrium condition.…”

Section: Introductionmentioning

confidence: 99%

Transient ionization potential depression in nonthermal dense plasmas at high x-ray intensity

et al. 2021

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The advent of x-ray free-electron lasers (XFELs), which provide intense ultrashort x-ray pulses, has brought a new way of creating and analyzing hot and warm dense plasmas in the laboratory. Because of the ultrashort pulse duration, the XFEL-produced plasma will be out of equilibrium at the beginning, and even the electronic subsystem may not reach thermal equilibrium while interacting with a femtosecond timescale pulse. In the dense plasma, the ionization potential depression (IPD) induced by the plasma environment plays a crucial role for understanding and modeling microscopic dynamical processes. However, all theoretical approaches for IPD have been based on local thermal equilibrium (LTE), and it has been controversial to use LTE IPD models for the nonthermal situation. In this work, we propose a non-LTE (NLTE) approach to calculate the IPD effect by combining a quantum-mechanical electronic-structure calculation and a classical molecular dynamics simulation. This hybrid approach enables us to investigate the time evolution of ionization potentials and IPDs during and after the interaction with XFEL pulses, without the limitation of the LTE assumption. In our NLTE approach, the transient IPD values are presented as distributions evolving with time, which cannot be captured by conventional LTE-based models. The time-integrated ionization potential values are in good agreement with benchmark experimental data on solid-density aluminum plasma and other theoretical predictions based on LTE. The present work is promising to provide critical insights into nonequilibrium dynamics of dense plasma formation and thermalization induced by XFEL pulses.

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“…Even though the electron plasma is treated separately, it undergoes nonequilibrium electron dynamics driven by intense XFEL pulses [55], which is anticipated by the fact that the electron-electron relaxation timescale [56][57][58] is comparable to the XFEL pulse duration. Furthermore, nonthermal femtosecond phase transitions induced by intense XFEL pulses have been reported [59,60]. Therefore, it is desirable to implement an IPD treatment that is unrestricted by the thermal equilibrium condition in the simulation.…”

Section: Introductionmentioning

confidence: 99%

Plasma environmental effects in the atomic structure for simulating x-ray free-electron-laser-heated solid-density matter

et al. 2022

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High energy density (HED) matter exists extensively in the Universe, and it can be created with extreme conditions in laboratory facilities such as x-ray free-electron lasers (XFEL). In HED matter, the electronic structure of individual atomic ions is influenced by a dense plasma environment, and one of the most significant phenomena is the ionization potential depression (IPD). Incorporation of the IPD effects is of great importance in accurate modeling of dense plasmas. All theoretical treatments of IPD so far have been based on the assumption of local thermodynamic equilibrium, but its validity is questionable in ultrafast formation dynamics of dense plasmas, particularly when interacting with intense XFEL pulses. A treatment of transient IPD, based on an electronic-structure calculation of an atom in the presence of a plasma environment described by classical particles, has recently been proposed [Phys. Rev. E 103, 023203 (2021)], but its application to and impact on plasma dynamics simulations have not been investigated yet. In this work, we extend XMDYN, a hybrid quantum-classical approach combining Monte Carlo and molecular dynamics, by incorporating the proposed IPD treatment into plasma dynamics simulations. We demonstrate the importance of the IPD effects in theoretical modeling of aluminum dense plasmas by comparing two XMDYN simulations: one with electronic-structure calculations of isolated atoms (without IPD) and the other with those of atoms embedded in a plasma (with IPD). At equilibrium, the mean charge obtained in the plasma simulation with IPD is in good agreement with the full quantum-mechanical average-atom model. The present approach promises to be a reliable tool to simulate the creation and nonequilibrium evolution of dense plasmas induced by ultraintense and ultrashort XFEL pulses.

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Femtosecond phase-transition in hard x-ray excited bismuth

Cited by 10 publications

References 36 publications

Delayed Onset and Directionality of X-Ray-Induced Atomic Displacements Observed on Subatomic Length Scales

Delayed Onset and Directionality of X-Ray-Induced Atomic Displacements Observed on Subatomic Length Scales

Transient ionization potential depression in nonthermal dense plasmas at high x-ray intensity

Plasma environmental effects in the atomic structure for simulating x-ray free-electron-laser-heated solid-density matter

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