The Experts below are selected from a list of 213 Experts worldwide ranked by ideXlab platform
Andrey Starikovskiy - One of the best experts on this subject based on the ideXlab platform.
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monte carlo simulation of the effect of Hot Atoms on active species kinetics in combustible mixtures excited by high voltage pulsed discharges
Combustion and Flame, 2017Co-Authors: N L Aleksandrov, Alexander Ponomarev, Andrey StarikovskiyAbstract:Abstract The energy degradation of fast H and O Atoms in H 2 :O 2 , CH 4 :O 2 and CH 4 :air mixtures is studied using Monte Carlo simulations, taking into account elastic collisions and chemical reactions. Based on the simulated results, the effect of high-energy Atoms on the amount and composition of chemically active species produced in high-voltage pulsed discharges is estimated. The obtained results are used to consider the contribution of “Hot” atom production to ignition and oxidation of fuel in combustible mixtures excited by nonequilibrium plasmas. It is shown that the presence of high-energy Atoms leads to a decrease in the specific deposited energy required for plasma-assisted ignition and an increase in the density of products of plasma-assisted oxidation at gas room temperature.
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Effect of translational nonequilibrium and “Hot” Atoms reactions on active species production in high-voltage pulsed discharges
2016 IEEE International Conference on Plasma Science (ICOPS), 2016Co-Authors: Nickolay Aleksandrov, Alexander Ponomarev, Andrey StarikovskiyAbstract:Dissociation of molecules by electron impact, dissociation by collisional quenching of electronically-excited states, and dissociative electron-ion and ion-ion recombination in nonequilibrium plasma, lead to formation of Atoms with excessive translational energy. Processes of these “Hot” Atoms formation in pulsed discharges at high overvoltage, TT-relaxation and chemical reactions with their participation are analyzed.
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On the role of 'Hot' Atoms in plasma-assisted ignition.
Philosophical transactions. Series A Mathematical physical and engineering sciences, 2015Co-Authors: Andrey StarikovskiyAbstract:This paper discusses the processes leading to the formation of ‘Hot’ Atoms and radicals possessing excessive translational energy in high-voltage NS pulse discharges. It is shown that the formation of such ‘Hot’ Atoms occurs efficiently both in the dissociation of molecules by direct electron impact, and in the collisional quenching of electronically excited states. Depending on the magnitude of the reduced electric field in the discharge, reactions of these ‘Hot’ Atoms increase the initial concentration of radicals in the discharge afterglow two to three times when compared with the values calculated without effects of translational non-equilibrium. The role of thermally non-equilibrium excitation has been demonstrated in the formation of the initial distribution of the chemically active components in the mixture and its influence on the kinetics of ignition initiation at low and high temperatures. It was found that in undiluted mixtures the presence of ‘Hot’ Atoms can significantly decrease an ignition threshold and accelerate a low-temperature oxidation.
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Plasma Assisted Combustion Mechanism for Small Hydrocarbons
Bulletin of the American Physical Society, 2014Co-Authors: Andrey Starikovskiy, Nickolay AleksandrovAbstract:Abstract : These briefing charts discuss Propulsion Efficiency and Operating Regimes for Variety of Flight Systems, Ignition, Combustion and Flame Control by Nonequilibrium Plasma, Lean Ignition for Gas IC Engines, Princeton Plasma Combustion Kinetics, Cross Sections, PAC Kinetic Mechanism, PAC Pathways, Potential Energy Curves of Molecular Hydrogen, Potential Energy Curves of Molecular Oxygen, Major Channels of Hot Atoms Production, Hexane Oxidation by Pulsed Nanosecond Discharge, Calculated and Measured Times of Oxidation, Plasma Shock Tube, Discharge Dynamics, and other results.
Bret Jackson - One of the best experts on this subject based on the ideXlab platform.
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the effects of lattice motion on eley rideal and Hot atom reactions quasiclassical studies of hydrogen recombination on ni 100
Journal of Physical Chemistry B, 2002Co-Authors: Ziya B Guvenc, Bret JacksonAbstract:Quasiclassical methods are used to simulate the interactions of H or D atom beams with D- or H-covered Ni(100) surfaces. The Ni substrate is treated as a multilayer slab, and the Ni Atoms are allowed to move. The model potential energy surface is fit to the results of detailed total-energy calculations based on density functional theory. Most of the incident Atoms trap to form Hot Atoms, which can eventually react with an adsorbate, or dissipate their energy and stick. The incident atom is found to lose several tenths of an eV of energy into the metal, upon initially colliding with the surface. This limits reflection to a few percent, at all coverages, and secondary reactions between adsorbates are significantly lowered. Long time Hot atom reactions are also found to be damped out by the inclusion of lattice motion, leading to increased sticking, even at high coverages where dissipation into the adsorbates should be the primary energy loss mechanism. Overall, the inclusion of lattice motion is found to improve agreement with experiment.
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eley rideal and Hot atom reactions of h d Atoms with d h covered cu 111 surfaces quasiclassical studies
Journal of Chemical Physics, 1999Co-Authors: Dmitrii V Shalashilin, Bret Jackson, Mats PerssonAbstract:Quasiclassical molecular dynamics studies are made of H or D Atoms incident from the gas phase onto D or H-covered Cu(111) surfaces. Two detailed model potential energy surfaces are used, both based on the results of extensive total energy calculations using the density functional method. The incident H (D) Atoms can react directly to form HD via the Eley–Rideal mechanism, or trap onto the surface. These trapped Hot Atoms can react with the adsorbates to form HD or can eventually dissipate enough energy through collisions with the adsorbates to become immobile. We also observe the formation of D2 (H2). Probabilities for these various processes, as well as the rotational, vibrational, and translational energy distributions of the products are computed and compared with experiment. Hot-atom pathways to product formation are shown to make significant contributions. One of the potentials gives excellent agreement with experiment, while the other is less successful.
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Eley-Rideal and Hot-atom reaction dynamics of H(g) with H adsorbed on Cu(111)
The Journal of Chemical Physics, 1997Co-Authors: Stavros Caratzoulas, Bret Jackson, Mats PerssonAbstract:Quasiclassical trajectory studies have been performed for the reaction between an H (or D) atom incident from the gas phase and a H (or D) atom adsorbed onto a Cu(111) surface. Results from a density functional calculation of the interaction between H and a Cu(111) surface are used to construct a detailed potential energy surface which contains all six nuclear degrees of freedom. Impacts of the incident atom close to the adsorbate can lead to direct Eley–Rideal reactions and the dynamics of these reactions are explored. Interaction of the incident atom with the adsorbate also results in trapping, with a high probability. This adsorbate-mediated trapping mechanism is important for impacts within 2 A of the adsorbate. At larger impact parameters scattering from the corrugation also leads to trapping. These trapped “Hot” Atoms can go on to react with an adsorbed species, and the dynamics of such Hot-atom reactions are explored. The final-state distributions of the products are examined with regard to isotope effects for the direct and Hot-atom pathways, and compared with experiment.
J. Brand - One of the best experts on this subject based on the ideXlab platform.
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spontaneous soliton formation and modulational instability in bose einstein condensates
Physical Review Letters, 2004Co-Authors: L. D. Carr, J. BrandAbstract:The dynamics of an elongated attractive Bose-Einstein condensate in an axisymmetric harmonic trap is studied. It is shown that density fringes caused by self-interference of the condensate order parameter seed modulational instability. The latter has novel features in contradistinction to the usual homogeneous case known from nonlinear fiber optics. Several open questions in the interpretation of the recent creation of the first matter-wave bright soliton train [K. E. Strecker et al., Nature (London) 417, 150 (2002).] are addressed. It is shown that primary transverse collapse, followed by secondary collapse induced by soliton-soliton interactions, produces bursts of Hot Atoms at different time scales.
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Spontaneous soliton formation and modulational instability in Bose-Einstein condensates
Physical Review Letters, 2004Co-Authors: L. D. Carr, J. BrandAbstract:The dynamics of an elongated attractive Bose-Einstein condensate in an axisymmetric harmonic trap is studied. It is shown that density fringes caused by self-interference of the condensate order parameter seed modulational instability. The latter has novel features in contradistinction to the usual homogeneous case known from nonlinear fiber optics. Several open questions in the interpretation of the recent creation of the first matter-wave bright soliton train [Strecker {\it et al.} Nature {\bf 417} 150 (2002)] are addressed. It is shown that primary transverse collapse, followed by secondary collapse induced by soliton--soliton interactions, produce bursts of Hot Atoms at different time scales.
Mats Persson - One of the best experts on this subject based on the ideXlab platform.
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eley rideal and Hot atom reactions of h d Atoms with d h covered cu 111 surfaces quasiclassical studies
Journal of Chemical Physics, 1999Co-Authors: Dmitrii V Shalashilin, Bret Jackson, Mats PerssonAbstract:Quasiclassical molecular dynamics studies are made of H or D Atoms incident from the gas phase onto D or H-covered Cu(111) surfaces. Two detailed model potential energy surfaces are used, both based on the results of extensive total energy calculations using the density functional method. The incident H (D) Atoms can react directly to form HD via the Eley–Rideal mechanism, or trap onto the surface. These trapped Hot Atoms can react with the adsorbates to form HD or can eventually dissipate enough energy through collisions with the adsorbates to become immobile. We also observe the formation of D2 (H2). Probabilities for these various processes, as well as the rotational, vibrational, and translational energy distributions of the products are computed and compared with experiment. Hot-atom pathways to product formation are shown to make significant contributions. One of the potentials gives excellent agreement with experiment, while the other is less successful.
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Eley-Rideal and Hot-atom reaction dynamics of H(g) with H adsorbed on Cu(111)
The Journal of Chemical Physics, 1997Co-Authors: Stavros Caratzoulas, Bret Jackson, Mats PerssonAbstract:Quasiclassical trajectory studies have been performed for the reaction between an H (or D) atom incident from the gas phase and a H (or D) atom adsorbed onto a Cu(111) surface. Results from a density functional calculation of the interaction between H and a Cu(111) surface are used to construct a detailed potential energy surface which contains all six nuclear degrees of freedom. Impacts of the incident atom close to the adsorbate can lead to direct Eley–Rideal reactions and the dynamics of these reactions are explored. Interaction of the incident atom with the adsorbate also results in trapping, with a high probability. This adsorbate-mediated trapping mechanism is important for impacts within 2 A of the adsorbate. At larger impact parameters scattering from the corrugation also leads to trapping. These trapped “Hot” Atoms can go on to react with an adsorbed species, and the dynamics of such Hot-atom reactions are explored. The final-state distributions of the products are examined with regard to isotope effects for the direct and Hot-atom pathways, and compared with experiment.
Saieswari Amaran - One of the best experts on this subject based on the ideXlab platform.
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Femtosecond two-pHoton pHotoassociation of Hot magnesium Atoms: A quantum dynamical study using thermal random phase wavefunctions
Journal of Chemical Physics, 2013Co-Authors: Saieswari Amaran, Leonid Rybak, Liat Levin, Robert Moszynski, Ronnie Kosloff, Zohar Amitay, Wojciech Skomorowski, Michał Tomza, Filip Pawłowski, J. Martin BerglundAbstract:Two-pHoton pHotoassociation of Hot magnesium Atoms by femtosecond laser pulses, creating electronically excited magnesium dimer molecules, is studied from first principles, combining ab initio quantum chemistry and molecular quantum dynamics. This theoretical framework allows for rationalizing the generation of molecular rovibrational coherence from thermally Hot Atoms [L. Rybak, S. Amaran, L. Levin, M. Tomza, R. Moszynski, R. Kosloff, C. P. Koch, and Z. Amitay, Phys. Rev. Lett. 107, 273001 (2011)]. Random phase thermal wavefunctions are employed to model the thermal ensemble of Hot colliding Atoms. Comparing two different choices of basis functions, random phase wavefunctions built from eigenstates are found to have the fastest convergence for the pHotoassociation yield. The interaction of the colliding Atoms with a femtosecond laser pulse is modeled non-perturbatively to account for strong-field effects.
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femtosecond two pHoton pHotoassociation of Hot magnesium Atoms a quantum dynamical study using thermal random phase wavefunctions
arXiv: Quantum Physics, 2012Co-Authors: Saieswari Amaran, Leonid Rybak, Liat Levin, Michal Tomza, Robert Moszynski, Ronnie Kosloff, Zohar Amitay, Wojciech Skomorowski, Filip Pawlowski, Martin J BerglundAbstract:Two-pHoton pHotoassociation of Hot magnesium Atoms by femtosecond laser pulses, creating electronically excited magnesium dimer molecules, is studied from first principles, combining \textit{ab initio} quantum chemistry and molecular quantum dynamics. This theoretical framework allows for rationalizing the generation of molecular rovibrational coherence from thermally Hot Atoms [L. Rybak \textit{et al.}, Phys. Rev. Lett. {\bf 107}, 273001 (2011)]. Random phase thermal wave functions are employed to model the thermal ensemble of Hot colliding Atoms. Comparing two different choices of basis functions, random phase wavefunctions built from eigenstates are found to have the fastest convergence for the pHotoassociation yield. The interaction of the colliding Atoms with a femtosecond laser pulse is modeled non-perturbatively to account for strong-field effects.
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generating molecular rovibrational coherence by two pHoton femtosecond pHotoassociation of thermally Hot Atoms
Physical Review Letters, 2011Co-Authors: Leonid Rybak, Saieswari Amaran, Liat Levin, Michal Tomza, Robert Moszynski, Ronnie Kosloff, Christiane P Koch, Zohar AmitayAbstract:The formation of diatomic molecules with rotational and vibrational coherence is demonstrated experimentally in free-to-bound two-pHoton femtosecond pHotoassociation of Hot Atoms. In a thermal gas at a temperature of 1000 K, pairs of magnesium Atoms, colliding in their electronic ground state, are excited into coherent superpositions of bound rovibrational levels in an electronically excited state. The rovibrational coherence is probed by a time-delayed third pHoton, resulting in quantum beats in the UV fluorescence. A comprehensive theoretical model based on ab initio calculations rationalizes the generation of coherence by Franck-Condon filtering of collision energies and partial waves, quantifying it in terms of an increase in quantum purity of the thermal ensemble. Our results open the way to coherent control of a binary reaction.