Nikita Shcheblanov | Université Claude Bernard Lyon 1 (original) (raw)

Papers by Nikita Shcheblanov

Research paper thumbnail of Early stage of the electron kinetics in swift heavy ion tracks in dielectrics

Physical Review B, 2010

A Monte-Carlo approach was applied for simulations of the early stage (first tens of fs) of kinet... more A Monte-Carlo approach was applied for simulations of the early stage (first tens of fs) of kinetics of the electronic subsystem of silica (SiO 2 ) in tracks of swift heavy ions (SHI) decelerated in the electronic stopping regime. At the first step multiple ionizations of target atoms by a projectile (Ca +19 , E = 11.4 MeV/amu) were described that gave the initial spatial distributions of free electrons having different momenta as well as distributions of holes in different atomic shells.

Research paper thumbnail of Effect of interaction of atomic electrons on ionization of an insulator in swift heavy ion tracks

Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 2012

describing excitation of the electronic subsystem of an insulator in tracks of swift heavy ions d... more describing excitation of the electronic subsystem of an insulator in tracks of swift heavy ions decelerated in the electronic stopping regime are investigated. The first mechanism is based on binary collisions of a fast projectile with atomic electrons considered as independent. The second one assumes redistribution of the energy transferred to an atom from an ion between the atomic electrons before autoionization of the excited atom. It is demonstrated that an appreciable difference occurs only in the kinetics of the most energetic electrons appeared during the ionization. This difference affects only a small fraction of the excess electronic energy in the far periphery of a track.

Research paper thumbnail of Effect of inter-atomic Auger processes on relaxation of electronic vacancies at deep levels of highly ionized atoms in swift heavy ion tracks

ABSTRACT We present the results of Monte-Carlo simulations of excitation and subsequent relaxatio... more ABSTRACT We present the results of Monte-Carlo simulations of excitation and subsequent relaxation of the electronic subsystem of quartz in the close vicinity of the swift heavy ion (SHI) trajectory. Comparison between numerical results and experiments detecting X-ray K-shell emission of silicon atoms (KαLn transitions) from quartz aerogel irradiated with SHIs demonstrated that the adequate description of the relaxation kinetics of the excited electronic subsystem of a solid in a SHI track cannot be possible without taking into account fast inter-atomic Auger processes which are absent in gaseous targets.

Research paper thumbnail of Effect of inter-atomic Auger processes on relaxation of electronic vacancies at deep levels of highly ionized atoms in swift heavy ion tracks

Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 2010

ABSTRACT We present the results of Monte-Carlo simulations of excitation and subsequent relaxatio... more ABSTRACT We present the results of Monte-Carlo simulations of excitation and subsequent relaxation of the electronic subsystem of quartz in the close vicinity of the swift heavy ion (SHI) trajectory. Comparison between numerical results and experiments detecting X-ray K-shell emission of silicon atoms (KαLn transitions) from quartz aerogel irradiated with SHIs demonstrated that the adequate description of the relaxation kinetics of the excited electronic subsystem of a solid in a SHI track cannot be possible without taking into account fast inter-atomic Auger processes which are absent in gaseous targets.

Research paper thumbnail of Electronic excitation and relaxation processes in femtosecond laser interactions with insulators: the role of laser wavelength, intensity and different absorption mechanisms

Numerical modeling of electronic excitation processes induced by ultra-short laser pulses in diel... more Numerical modeling of electronic excitation processes induced by ultra-short laser pulses in dielectric materials is performed. The developed model is based on a detailed kinetic description and accounts for the absence of equilibrium in the electronic subsystem. The photoionization process is first analyzed for different laser intensities. It is shown that the probability of this process depends strongly on the Keldysh parameter and effective ionization potential, which are calculated as a function of the laser field. Electron energy distributions are calculated and the average energy is analyzed as a function of laser parameters. For laser intensities corresponding to the maximum of this dependency, only around 1% of electrons are shown to achieve the energy required for the impact ionization.

Research paper thumbnail of Photo-excitation and carrier relaxation in semiconductor tip under high dc electric field during laser-assisted atom probe tomography analysis

Research paper thumbnail of Ultra-short laser induced electron excitation/relaxation kinetics

Research paper thumbnail of Detailed analysis of plastic shear in the Raman spectra of SiO2 glass

Journal of Non-Crystalline Solids, 2015

Research paper thumbnail of Numerical Analysis of Ultra-Short Laser Interactions with Dielectric Materials

Laser-induced electronic excitation, absorption and relaxation are the key issues in ultra-short ... more Laser-induced electronic excitation, absorption and relaxation are the key issues in ultra-short laser interactions with dielectric materials. To numerically analyze these processes, a detailed non-equilibrium model is developed based on the kinetic Boltzmann equations without any appeal to the classical Drude model. The calculations yield not only electron density in the conduction band, but also their energy distribution allowing a better analysis of the role of avalanche ionization. The calculations performed reveal a remarkable effect of the laser-field on collision frequencies resulting in smaller free-carriers absorption than the one predicted by commonly used rate-equation models. Furthermore, both electron-electron and electron-phonon relaxation are examined, and the energy of the electron sub-system is investigated as a function of laser fluence and pulse duration. Because efficient bond breaking requires energy, these calculations provide the required thresholds.

Research paper thumbnail of Raman measurement of irreversible shear in SiO $ _2 $ glass

Research paper thumbnail of Collision frequencies and absorption calculations for ultra-short laser interactions with dielectric materials

Fundamentals of Laser-Assisted Micro- and Nanotechnologies 2013, 2013

Laser-induced electronic excitation, absorption and relaxation are the key issues in ultra-short ... more Laser-induced electronic excitation, absorption and relaxation are the key issues in ultra-short laser interactions with dielectric materials. To numerically analyze these processes, a detailed non-equilibrium model is developed based on the kinetic Boltzmann equations without any appeal to the classical Drude model. The calculations are performed including all possible collisional processes. As a result, electron energy distributions are obtained allowing a better analysis of ultra-short laser interactions. A remarkable effect of the laser-field on collision frequencies is demonstrated leading to smaller free-carriers absorption than the one predicted by Drude model with a non-field dependent collision frequency. Both electron-electron and electron-phonon relaxation are then examined, and the mean energy density of the electron sub-system is investigated as a function of laser fluence and pulse duration. The developed model is useful for many laser applications including high precision in laser treatment, laser-assisted atomic probe tomography, and for the development of new powerful laser systems.

Research paper thumbnail of Laser Applications for Nanotechnology: Insights From Numerical Modeling

International Symposium on High Power Laser Ablation 2010, 2010

Laser‐produced nanoparticles have found many applications in bio‐photonics, medicine and in the d... more Laser‐produced nanoparticles have found many applications in bio‐photonics, medicine and in the development of photovolvatic cells. Many experiments have been performed demonstrating the formation of these particles from solid targets in vacuum, in the ...

Research paper thumbnail of Femtosecond Laser Interactions with Semiconductor and Dielectric Materials

International Symposium on High Power Laser Ablation 2012, 2012

ABSTRACT Electronic excitation-relaxation processes induced by ultra-short laser pulses are studi... more ABSTRACT Electronic excitation-relaxation processes induced by ultra-short laser pulses are studied numerically for semiconductors and dielectric materials (Si, quartz). A detailed kinetic approach is used in the calculations accounting for electron-photon-phonon, electron-phonon and electron-electron scatterings. In addition, both laser field ionization ranging from multi-photon to tunneling one, and electron impact (avalanche) ionization processes are included in the model. Based on the performed calculations we study the relaxation time as a function of laser parameters. It is shown that this time depends on the density of the created free carriers, which in turn is a nonlinear function of laser intensity. In addition, a simple damage criterion is proposed based on the mean electron energy density rather than on critical free electron density. This criterion gives a reasonable agreement with the available experimental data practically without adjustable parameters. Furthermore, the performed modeling provides energy absorbed in the target, conditions for damage of dielectric materials, as well as conditions for surface plasmon excitation and for periodic surface structure formation on the surface of semiconductor materials.

Research paper thumbnail of Early stage of the electron kinetics in swift heavy ion tracks in dielectrics

Physical Review B, 2010

A Monte-Carlo approach was applied for simulations of the early stage (first tens of fs) of kinet... more A Monte-Carlo approach was applied for simulations of the early stage (first tens of fs) of kinetics of the electronic subsystem of silica (SiO 2 ) in tracks of swift heavy ions (SHI) decelerated in the electronic stopping regime. At the first step multiple ionizations of target atoms by a projectile (Ca +19 , E = 11.4 MeV/amu) were described that gave the initial spatial distributions of free electrons having different momenta as well as distributions of holes in different atomic shells.

Research paper thumbnail of Effect of interaction of atomic electrons on ionization of an insulator in swift heavy ion tracks

Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 2012

describing excitation of the electronic subsystem of an insulator in tracks of swift heavy ions d... more describing excitation of the electronic subsystem of an insulator in tracks of swift heavy ions decelerated in the electronic stopping regime are investigated. The first mechanism is based on binary collisions of a fast projectile with atomic electrons considered as independent. The second one assumes redistribution of the energy transferred to an atom from an ion between the atomic electrons before autoionization of the excited atom. It is demonstrated that an appreciable difference occurs only in the kinetics of the most energetic electrons appeared during the ionization. This difference affects only a small fraction of the excess electronic energy in the far periphery of a track.

Research paper thumbnail of Electronic excitation and relaxation processes in wide band gap dielectric materials in the transition region of the Keldysh parameter

Applied Surface Science, 2012

Numerical modeling of electronic excitation processes induced by ultra-short laser pulses in diel... more Numerical modeling of electronic excitation processes induced by ultra-short laser pulses in dielectric materials is performed. The developed model is based on a detailed kinetic description and accounts for the absence of equilibrium in the electronic subsystem. The photoionization process is first analyzed for different laser intensities. It is shown that the probability of this process depends strongly on the Keldysh parameter and effective ionization potential, which are calculated as a function of the laser field. Electron energy distributions are calculated and the average energy is analyzed as a function of laser parameters. For laser intensities corresponding to the maximum of this dependency, only around 1% of electrons are shown to achieve the energy required for the impact ionization.

Research paper thumbnail of Numerical study of femtosecond laser-assisted atom probe tomography

Applied Physics A, 2013

We investigate the mechanisms of a laser-assisted atom probe tomography technique. In this method... more We investigate the mechanisms of a laser-assisted atom probe tomography technique. In this method, a subwavelength tip is subjected both to a very strong static electric field and to a femtosecond laser pulse. As a result, ions are ejected from the tip one by one. By using femtosecond lasers, one can analyze not only metals but also semiconductors and dielectric materials. To better understand the ejection process, a numerical model is developed based on the drift-diffusion approach. The model accounts for such effects as field penetration, hole and electron movement, and laser absorption. For the given value of the dc field, a substantial band bending and an increase in hole density at the surface of the silicon tip are observed. This bending effect changes silicon absorption coefficient at the surface and significantly increases recombination time of laser-induced carriers.

Research paper thumbnail of Femtosecond laser interactions with dielectric materials: insights of a detailed modeling of electronic excitation and relaxation processes

Applied Physics A, 2013

Your article is protected by copyright and all rights are held exclusively by Springer-Verlag. Th... more Your article is protected by copyright and all rights are held exclusively by Springer-Verlag. This e-offprint is for personal use only and shall not be self-archived in electronic repositories. If you wish to self-archive your work, please use the accepted author's version for posting to your own website or your institution's repository. You may further deposit the accepted author's version on a funder's repository at a funder's request, provided it is not made publicly available until 12 months after publication.

Research paper thumbnail of Electronic excitation in femtosecond laser interactions with wide-band-gap materials

Applied Physics A-materials Science & Processing, 2010

Effects of the ultrashort laser excitations of wide-band-gap materials are investigated. Single-,... more Effects of the ultrashort laser excitations of wide-band-gap materials are investigated. Single-, double-, and multiple-shot cases are considered with a particular focus on the control over the transient reflectivity changes and the energy deposition rate. We show that the history of laser excitations affects not only the ionization process and the final number of the conduction-band electrons, but also determines the reflectivity time evolution and the rate of laser energy deposition into the target. Based on the obtained calculation results, both thermal effects and structural modifications can be better controlled.

Research paper thumbnail of Early stage of the electron kinetics in swift heavy ion tracks in dielectrics

Physical Review B, 2010

A Monte-Carlo approach was applied for simulations of the early stage (first tens of fs) of kinet... more A Monte-Carlo approach was applied for simulations of the early stage (first tens of fs) of kinetics of the electronic subsystem of silica (SiO 2 ) in tracks of swift heavy ions (SHI) decelerated in the electronic stopping regime. At the first step multiple ionizations of target atoms by a projectile (Ca +19 , E = 11.4 MeV/amu) were described that gave the initial spatial distributions of free electrons having different momenta as well as distributions of holes in different atomic shells.

Research paper thumbnail of Effect of interaction of atomic electrons on ionization of an insulator in swift heavy ion tracks

Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 2012

describing excitation of the electronic subsystem of an insulator in tracks of swift heavy ions d... more describing excitation of the electronic subsystem of an insulator in tracks of swift heavy ions decelerated in the electronic stopping regime are investigated. The first mechanism is based on binary collisions of a fast projectile with atomic electrons considered as independent. The second one assumes redistribution of the energy transferred to an atom from an ion between the atomic electrons before autoionization of the excited atom. It is demonstrated that an appreciable difference occurs only in the kinetics of the most energetic electrons appeared during the ionization. This difference affects only a small fraction of the excess electronic energy in the far periphery of a track.

Research paper thumbnail of Effect of inter-atomic Auger processes on relaxation of electronic vacancies at deep levels of highly ionized atoms in swift heavy ion tracks

ABSTRACT We present the results of Monte-Carlo simulations of excitation and subsequent relaxatio... more ABSTRACT We present the results of Monte-Carlo simulations of excitation and subsequent relaxation of the electronic subsystem of quartz in the close vicinity of the swift heavy ion (SHI) trajectory. Comparison between numerical results and experiments detecting X-ray K-shell emission of silicon atoms (KαLn transitions) from quartz aerogel irradiated with SHIs demonstrated that the adequate description of the relaxation kinetics of the excited electronic subsystem of a solid in a SHI track cannot be possible without taking into account fast inter-atomic Auger processes which are absent in gaseous targets.

Research paper thumbnail of Effect of inter-atomic Auger processes on relaxation of electronic vacancies at deep levels of highly ionized atoms in swift heavy ion tracks

Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 2010

ABSTRACT We present the results of Monte-Carlo simulations of excitation and subsequent relaxatio... more ABSTRACT We present the results of Monte-Carlo simulations of excitation and subsequent relaxation of the electronic subsystem of quartz in the close vicinity of the swift heavy ion (SHI) trajectory. Comparison between numerical results and experiments detecting X-ray K-shell emission of silicon atoms (KαLn transitions) from quartz aerogel irradiated with SHIs demonstrated that the adequate description of the relaxation kinetics of the excited electronic subsystem of a solid in a SHI track cannot be possible without taking into account fast inter-atomic Auger processes which are absent in gaseous targets.

Research paper thumbnail of Electronic excitation and relaxation processes in femtosecond laser interactions with insulators: the role of laser wavelength, intensity and different absorption mechanisms

Numerical modeling of electronic excitation processes induced by ultra-short laser pulses in diel... more Numerical modeling of electronic excitation processes induced by ultra-short laser pulses in dielectric materials is performed. The developed model is based on a detailed kinetic description and accounts for the absence of equilibrium in the electronic subsystem. The photoionization process is first analyzed for different laser intensities. It is shown that the probability of this process depends strongly on the Keldysh parameter and effective ionization potential, which are calculated as a function of the laser field. Electron energy distributions are calculated and the average energy is analyzed as a function of laser parameters. For laser intensities corresponding to the maximum of this dependency, only around 1% of electrons are shown to achieve the energy required for the impact ionization.

Research paper thumbnail of Photo-excitation and carrier relaxation in semiconductor tip under high dc electric field during laser-assisted atom probe tomography analysis

Research paper thumbnail of Ultra-short laser induced electron excitation/relaxation kinetics

Research paper thumbnail of Detailed analysis of plastic shear in the Raman spectra of SiO2 glass

Journal of Non-Crystalline Solids, 2015

Research paper thumbnail of Numerical Analysis of Ultra-Short Laser Interactions with Dielectric Materials

Laser-induced electronic excitation, absorption and relaxation are the key issues in ultra-short ... more Laser-induced electronic excitation, absorption and relaxation are the key issues in ultra-short laser interactions with dielectric materials. To numerically analyze these processes, a detailed non-equilibrium model is developed based on the kinetic Boltzmann equations without any appeal to the classical Drude model. The calculations yield not only electron density in the conduction band, but also their energy distribution allowing a better analysis of the role of avalanche ionization. The calculations performed reveal a remarkable effect of the laser-field on collision frequencies resulting in smaller free-carriers absorption than the one predicted by commonly used rate-equation models. Furthermore, both electron-electron and electron-phonon relaxation are examined, and the energy of the electron sub-system is investigated as a function of laser fluence and pulse duration. Because efficient bond breaking requires energy, these calculations provide the required thresholds.

Research paper thumbnail of Raman measurement of irreversible shear in SiO $ _2 $ glass

Research paper thumbnail of Collision frequencies and absorption calculations for ultra-short laser interactions with dielectric materials

Fundamentals of Laser-Assisted Micro- and Nanotechnologies 2013, 2013

Laser-induced electronic excitation, absorption and relaxation are the key issues in ultra-short ... more Laser-induced electronic excitation, absorption and relaxation are the key issues in ultra-short laser interactions with dielectric materials. To numerically analyze these processes, a detailed non-equilibrium model is developed based on the kinetic Boltzmann equations without any appeal to the classical Drude model. The calculations are performed including all possible collisional processes. As a result, electron energy distributions are obtained allowing a better analysis of ultra-short laser interactions. A remarkable effect of the laser-field on collision frequencies is demonstrated leading to smaller free-carriers absorption than the one predicted by Drude model with a non-field dependent collision frequency. Both electron-electron and electron-phonon relaxation are then examined, and the mean energy density of the electron sub-system is investigated as a function of laser fluence and pulse duration. The developed model is useful for many laser applications including high precision in laser treatment, laser-assisted atomic probe tomography, and for the development of new powerful laser systems.

Research paper thumbnail of Laser Applications for Nanotechnology: Insights From Numerical Modeling

International Symposium on High Power Laser Ablation 2010, 2010

Laser‐produced nanoparticles have found many applications in bio‐photonics, medicine and in the d... more Laser‐produced nanoparticles have found many applications in bio‐photonics, medicine and in the development of photovolvatic cells. Many experiments have been performed demonstrating the formation of these particles from solid targets in vacuum, in the ...

Research paper thumbnail of Femtosecond Laser Interactions with Semiconductor and Dielectric Materials

International Symposium on High Power Laser Ablation 2012, 2012

ABSTRACT Electronic excitation-relaxation processes induced by ultra-short laser pulses are studi... more ABSTRACT Electronic excitation-relaxation processes induced by ultra-short laser pulses are studied numerically for semiconductors and dielectric materials (Si, quartz). A detailed kinetic approach is used in the calculations accounting for electron-photon-phonon, electron-phonon and electron-electron scatterings. In addition, both laser field ionization ranging from multi-photon to tunneling one, and electron impact (avalanche) ionization processes are included in the model. Based on the performed calculations we study the relaxation time as a function of laser parameters. It is shown that this time depends on the density of the created free carriers, which in turn is a nonlinear function of laser intensity. In addition, a simple damage criterion is proposed based on the mean electron energy density rather than on critical free electron density. This criterion gives a reasonable agreement with the available experimental data practically without adjustable parameters. Furthermore, the performed modeling provides energy absorbed in the target, conditions for damage of dielectric materials, as well as conditions for surface plasmon excitation and for periodic surface structure formation on the surface of semiconductor materials.

Research paper thumbnail of Early stage of the electron kinetics in swift heavy ion tracks in dielectrics

Physical Review B, 2010

A Monte-Carlo approach was applied for simulations of the early stage (first tens of fs) of kinet... more A Monte-Carlo approach was applied for simulations of the early stage (first tens of fs) of kinetics of the electronic subsystem of silica (SiO 2 ) in tracks of swift heavy ions (SHI) decelerated in the electronic stopping regime. At the first step multiple ionizations of target atoms by a projectile (Ca +19 , E = 11.4 MeV/amu) were described that gave the initial spatial distributions of free electrons having different momenta as well as distributions of holes in different atomic shells.

Research paper thumbnail of Effect of interaction of atomic electrons on ionization of an insulator in swift heavy ion tracks

Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 2012

describing excitation of the electronic subsystem of an insulator in tracks of swift heavy ions d... more describing excitation of the electronic subsystem of an insulator in tracks of swift heavy ions decelerated in the electronic stopping regime are investigated. The first mechanism is based on binary collisions of a fast projectile with atomic electrons considered as independent. The second one assumes redistribution of the energy transferred to an atom from an ion between the atomic electrons before autoionization of the excited atom. It is demonstrated that an appreciable difference occurs only in the kinetics of the most energetic electrons appeared during the ionization. This difference affects only a small fraction of the excess electronic energy in the far periphery of a track.

Research paper thumbnail of Electronic excitation and relaxation processes in wide band gap dielectric materials in the transition region of the Keldysh parameter

Applied Surface Science, 2012

Numerical modeling of electronic excitation processes induced by ultra-short laser pulses in diel... more Numerical modeling of electronic excitation processes induced by ultra-short laser pulses in dielectric materials is performed. The developed model is based on a detailed kinetic description and accounts for the absence of equilibrium in the electronic subsystem. The photoionization process is first analyzed for different laser intensities. It is shown that the probability of this process depends strongly on the Keldysh parameter and effective ionization potential, which are calculated as a function of the laser field. Electron energy distributions are calculated and the average energy is analyzed as a function of laser parameters. For laser intensities corresponding to the maximum of this dependency, only around 1% of electrons are shown to achieve the energy required for the impact ionization.

Research paper thumbnail of Numerical study of femtosecond laser-assisted atom probe tomography

Applied Physics A, 2013

We investigate the mechanisms of a laser-assisted atom probe tomography technique. In this method... more We investigate the mechanisms of a laser-assisted atom probe tomography technique. In this method, a subwavelength tip is subjected both to a very strong static electric field and to a femtosecond laser pulse. As a result, ions are ejected from the tip one by one. By using femtosecond lasers, one can analyze not only metals but also semiconductors and dielectric materials. To better understand the ejection process, a numerical model is developed based on the drift-diffusion approach. The model accounts for such effects as field penetration, hole and electron movement, and laser absorption. For the given value of the dc field, a substantial band bending and an increase in hole density at the surface of the silicon tip are observed. This bending effect changes silicon absorption coefficient at the surface and significantly increases recombination time of laser-induced carriers.

Research paper thumbnail of Femtosecond laser interactions with dielectric materials: insights of a detailed modeling of electronic excitation and relaxation processes

Applied Physics A, 2013

Your article is protected by copyright and all rights are held exclusively by Springer-Verlag. Th... more Your article is protected by copyright and all rights are held exclusively by Springer-Verlag. This e-offprint is for personal use only and shall not be self-archived in electronic repositories. If you wish to self-archive your work, please use the accepted author's version for posting to your own website or your institution's repository. You may further deposit the accepted author's version on a funder's repository at a funder's request, provided it is not made publicly available until 12 months after publication.

Research paper thumbnail of Electronic excitation in femtosecond laser interactions with wide-band-gap materials

Applied Physics A-materials Science & Processing, 2010

Effects of the ultrashort laser excitations of wide-band-gap materials are investigated. Single-,... more Effects of the ultrashort laser excitations of wide-band-gap materials are investigated. Single-, double-, and multiple-shot cases are considered with a particular focus on the control over the transient reflectivity changes and the energy deposition rate. We show that the history of laser excitations affects not only the ionization process and the final number of the conduction-band electrons, but also determines the reflectivity time evolution and the rate of laser energy deposition into the target. Based on the obtained calculation results, both thermal effects and structural modifications can be better controlled.