63 citations · 534 across the 24 of their papers we have counts for
24 papers
Electron-phonon coupling in semiconductors at high electronic temperatures
Nikita Medvedev
A nonperturbative dynamical coupling approach based on tight-binding molecular dynamics is used to evaluate the electron-ion (electron-phonon) coupling parameter in irradiated semi…
Atomic-Scale Insights into Damage Produced by Swift Heavy Ions in Polyethylene
P. Babaev, F. Akhmetov, S. Gorbunov +4
We describe the formation of swift heavy ion tracks in polyethylene (PE) by combining the Monte Carlo code TREKIS, which models electronic excitation in nanometric proximity of the…
XTANT-3: X-ray-induced Thermal And Nonthermal Transitions in matter: theory, numerical details, user manual
Nikita Medvedev
This is the user manual for the hybrid code XTANT-3, simulating intense femtosecond X-ray irradiation of matter. The code combines a few models into one with feedbacks: transport M…
Materials under XUV irradiation: effects of structure, size, and temperature
Nikita Medvedev
This proceeding discusses the impact of XUV/X-ray irradiation on materials, and how their response is affected by temperature, size, and structure. When materials are exposed to in…
Revealing Non-equilibrium and Relaxation in Warm Dense Matter
Jan Vorberger, Thomas R. Preston, Nikita Medvedev +4
Experiments creating extreme states of matter almost invariably create non-equilibrium states. These are very interesting in their own right but need to be understood even if the u…
Electronic nonequilibrium effect in ultrafast-laser-irradiated solids
Nikita Medvedev
This paper describes the effects of electronic nonequilibrium in a simulation of ultrafast laser irradiation of materials. The simulation scheme based on tight-binding molecular dy…
Metallic water: transient state under ultrafast electronic excitation
Nikita Medvedev, Roman Voronkov, Alexander E. Volkov
The modern means of controlled irradiation by femtosecond lasers or swift heavy ion beams can transiently produce such energy densities in samples that reach collective electronic…
Frontiers, challenges, and solutions in modeling of swift heavy ion effects in materials
N. Medvedev, A. E. Volkov, R. Rymzhanov +4
Since a few breakthroughs in the fundamental understanding of the effects of swift heavy ions (SHI) decelerating in the electronic stopping regime in the matter have been achieved…
Damage threshold in pre-heated materials exposed to intense X-rays
Nikita Medvedev, Zuzana Kuglerová, Mikako Makita +2
Materials exposed to ultrashort intense x-ray irradiation may experience various damaging conditions depending on the in-situ temperature. A pre-heated target exposed to intense x-…
Nonthermal effects in solids after swift heavy ion impact
N. Medvedev, R. Voronkov, A. E. Volkov
This contribution is a brief introduction to nonthermal effects related to modifications of the interatomic potential upon ultrafast excitation of the electronic system of solids,…
Laser-induced electron dynamics and surface modification in ruthenium thin films
Fedor Akhmetov, Igor Milov, Sergey Semin +7
We performed the experimental and theoretical study of the heating and damaging of ruthenium thin films induced by femtosecond laser irradiation. Results of an optical pump-probe t…
Modeling time-resolved kinetics in solids induced by extreme electronic excitation
N. Medvedev, F. Akhmetov, R. A. Rymzhanov +2
We present a concurrent Monte Carlo (MC) - molecular dynamics (MD) approach to modeling of matter response to excitation of its electronic system. The two methods are combined on-t…
Superionic states formation in group III oxides irradiated with ultrafast lasers
R. A. Voronkov, N. Medvedev, A. E. Volkov
A number of group III-metal oxides are studied via density functional theory in order to establish a possibility of nonthermal transition of these materials into a superionic state…
Reconciling anomalously fast heating rate in ion tracks with low electron-phonon coupling
Nikita Medvedev, Alexander E. Volkov
Formation of swift heavy ion tracks requires extremely fast energy transfer between excited electrons and a lattice. However, electron-phonon energy exchange is too slow, as known…
Electron cascades and secondary electron emission in graphene under energetic ion irradiation
Henrique Vázquez, Alina Kononov, Andreas Kyritsakis +3
Highly energetic ions traversing a two-dimensional material such as graphene produce strong electronic excitations. Electrons excited to energy states above the work function can g…
Dependence of nonthermal metallization kinetics on bond ionicity of compounds
R. A. Voronkov, N. Medvedev, A. E. Volkov
It is known that covalently bonded materials undergo nonthermal structure transformations upon ultrafast excitation of an electronic system, whereas metals exhibit phonon hardening…
Mechanisms of surface nanostructuring of Al2O3 and MgO by grazing incidence irradiation with swift heavy ions
Marko Karlusic, Ruslan A. Rymzhanov, Jacques H. O'Connell +10
We experimentally discovered that Al2O3 and MgO exhibit well-pronounced nanometric modifications on the surfaces when irradiated under grazing incidence with 23 MeV I beam, in cont…
Fundamental Phenomena and Applications of Swift Heavy Ion Irradiations
Maik Lang, Flyura Djurabekova, Nikita Medvedev +2
This review concentrates on the specific properties and characteristics of damage structures generated with high-energy ions in the electronic energy loss regime. Irradiation exper…
Modeling warm dense matter formation within tight binding approximation
Nikita Medvedev
This contribution discusses challenges in the modeling of formation of the warm dense matter (WDM) state in solids exposed to femtosecond X-ray free-electron laser pulses. It is ba…
Multistep transition of diamond to warm dense matter state revealed by femtosecond X-ray diffraction
Nikita Medvedev, Beata Ziaja
Diamond bulk irradiated with a free-electron laser pulse of 6100 eV photon energy, 5 fs duration, at the eV/atom absorbed doses, is studied theoretically on its way to…
Electronic and atomic kinetics in solids irradiated with free-electron lasers or swift-heavy ions
N. Medvedev, A. E. Volkov, B. Ziaja
In this brief review we discuss the transient processes in solids under irradiation with femtosecond X-ray free-electron-laser (FEL) pulses and swift-heavy ions (SHI). Both kinds o…
Soft x-rays induce femtosecond solid-to-solid phase transition
Franz Tavella, Hauke Höppner, Victor Tkachenko +12
Soft x-rays were applied to induce graphitization of diamond through a non-thermal solid-to-solid phase transition. This process was observed within poly-crystalline diamond with a…
Effects of model approximations for electron, hole, and photon transport in swift heavy ion tracks
R. A. Rymzhanov, N. A. Medvedev, A. E. Volkov
The event-by-event Monte Carlo code, TREKIS, was recently developed to describe excitation of the electron subsystems of solids in the nanometric vicinity of a trajectory of a nonr…
Time-resolved observation of band-gap shrinking and electron-lattice thermalization within X-ray excited gallium arsenide
Beata Ziaja, Nikita Medvedev, Victor Tkachenko +2
Femtosecond X-ray irradiation of solids excites energetic photoelectrons that thermalize on a timescale of a few hundred femtoseconds. The thermalized electrons exchange energy wit…