The Experts below are selected from a list of 25809 Experts worldwide ranked by ideXlab platform
Hongguang Duan - One of the best experts on this subject based on the ideXlab platform.
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signature of the geometric phase in the Wave Packet dynamics on hypersurfaces
Chemical Physics, 2018Co-Authors: Hongguang Duan, Zhenrong Sun, R Dwayne J Miller, Michael ThorwartAbstract:Abstract We study the nonadiabatic dynamics of an electronic Wave Packet on two coupled potential energy surfaces. We focus on the difference between two configurations, the presence of a conical intersection (CI) and an avoided crossing (AC). We project the time-dependent dynamics onto the tuning and the coupling modes. For weak intersurface coupling, no significant difference appears. However, significant differences in the deactivation of the Wave Packet arise for increasing intersurface coupling. Most striking is a strong destructive interference of the two pathways of the Wave Packet which differ by a factor of π when moving around the CI. This yields to a vanishing of the Wave Packet in the CI configuration, which does not exist with an avoided crossing. By this, it is straightforward to identify the geometric phase in the Wave Packet dynamics and to use it to distinguish a CI from an AC configuration.
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tracking an electronic Wave Packet in the vicinity of a conical intersection
Journal of Chemical Physics, 2017Co-Authors: Hongguang Duan, Zhenrong Sun, R Dwayne J Miller, Michael ThorwartAbstract:This work treats the impact of vibrational coherence on the quantum efficiency of a dissipative electronic Wave Packet in the vicinity of a conical intersection by monitoring the time-dependent Wave Packet projection onto the tuning and the coupling mode. The vibrational coherence of the Wave Packet is tuned by varying the strength of the dissipative vibrational coupling of the tuning and the coupling modes to their thermal baths. We observe that the most coherent Wave Packet yields a quantum efficiency of 93%, but with a large transfer time constant. The quantum yield is dramatically decreased to 50% for a strongly damped incoherent Wave Packet, but the associated transfer time of the strongly localized Wave Packet is short. In addition, we find for the strongly damped Wave Packet that the transfer occurs via tunneling of the Wave Packet between the potential energy surfaces before the seam of the conical intersection is reached and a direct passage takes over. Our results provide direct evidence that vibrational coherence of the electronic Wave Packet is a decisive factor which determines the dynamical behavior of a Wave Packet in the vicinity of the conical intersection.
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quantum mechanical Wave Packet dynamics at a conical intersection with strong vibrational dissipation
Journal of Physical Chemistry Letters, 2016Co-Authors: Hongguang Duan, Michael ThorwartAbstract:We derive a reduced model for the nonadiabatic quantum dynamics of an electronic Wave Packet moving through a conical intersection in the presence of strong vibrational damping. Starting from the dissipative two-state two-model model, we transform the tuning and the coupling mode to the bath. The resulting quantum two-state model with two highly structured environments is solved numerically exactly in the regime of strong vibrational damping. We find negative cross peaks in the ultrafast optical 2D spectra as clear signatures of the conical intersection. They arise from secondary excitations of the Wave Packet after having passed through the photophysical energy funnel. This feature is in agreement with recent transient absorption measurements of rhodopsin.
Michael Thorwart - One of the best experts on this subject based on the ideXlab platform.
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signature of the geometric phase in the Wave Packet dynamics on hypersurfaces
Chemical Physics, 2018Co-Authors: Hongguang Duan, Zhenrong Sun, R Dwayne J Miller, Michael ThorwartAbstract:Abstract We study the nonadiabatic dynamics of an electronic Wave Packet on two coupled potential energy surfaces. We focus on the difference between two configurations, the presence of a conical intersection (CI) and an avoided crossing (AC). We project the time-dependent dynamics onto the tuning and the coupling modes. For weak intersurface coupling, no significant difference appears. However, significant differences in the deactivation of the Wave Packet arise for increasing intersurface coupling. Most striking is a strong destructive interference of the two pathways of the Wave Packet which differ by a factor of π when moving around the CI. This yields to a vanishing of the Wave Packet in the CI configuration, which does not exist with an avoided crossing. By this, it is straightforward to identify the geometric phase in the Wave Packet dynamics and to use it to distinguish a CI from an AC configuration.
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tracking an electronic Wave Packet in the vicinity of a conical intersection
Journal of Chemical Physics, 2017Co-Authors: Hongguang Duan, Zhenrong Sun, R Dwayne J Miller, Michael ThorwartAbstract:This work treats the impact of vibrational coherence on the quantum efficiency of a dissipative electronic Wave Packet in the vicinity of a conical intersection by monitoring the time-dependent Wave Packet projection onto the tuning and the coupling mode. The vibrational coherence of the Wave Packet is tuned by varying the strength of the dissipative vibrational coupling of the tuning and the coupling modes to their thermal baths. We observe that the most coherent Wave Packet yields a quantum efficiency of 93%, but with a large transfer time constant. The quantum yield is dramatically decreased to 50% for a strongly damped incoherent Wave Packet, but the associated transfer time of the strongly localized Wave Packet is short. In addition, we find for the strongly damped Wave Packet that the transfer occurs via tunneling of the Wave Packet between the potential energy surfaces before the seam of the conical intersection is reached and a direct passage takes over. Our results provide direct evidence that vibrational coherence of the electronic Wave Packet is a decisive factor which determines the dynamical behavior of a Wave Packet in the vicinity of the conical intersection.
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quantum mechanical Wave Packet dynamics at a conical intersection with strong vibrational dissipation
Journal of Physical Chemistry Letters, 2016Co-Authors: Hongguang Duan, Michael ThorwartAbstract:We derive a reduced model for the nonadiabatic quantum dynamics of an electronic Wave Packet moving through a conical intersection in the presence of strong vibrational damping. Starting from the dissipative two-state two-model model, we transform the tuning and the coupling mode to the bath. The resulting quantum two-state model with two highly structured environments is solved numerically exactly in the regime of strong vibrational damping. We find negative cross peaks in the ultrafast optical 2D spectra as clear signatures of the conical intersection. They arise from secondary excitations of the Wave Packet after having passed through the photophysical energy funnel. This feature is in agreement with recent transient absorption measurements of rhodopsin.
J Ullrich - One of the best experts on this subject based on the ideXlab platform.
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spatiotemporal imaging of ultrafast molecular motion collapse and revival of the d 2 nuclear Wave Packet
Physical Review Letters, 2006Co-Authors: Th Ergler, Artem Rudenko, B Feuerstein, K Zrost, C D Schroter, R Moshammer, J UllrichAbstract:We report on a real-time imaging of the ultrafast D{sub 2}{sup +} rovibrational nuclear Wave-Packet motion performed using a combination of a pump-probe setup with 7 fs laser pulses and a 'reaction-microscope' spectrometer. We observe fast dephasing (collapse) of the vibrational Wave Packet and its subsequent revival and prove rotational excitation in ultrashort laser pulses. Channel-selective Fourier analysis of the Wave Packet's long-term ({approx}3000 fs) evolution allows us to resolve its individual constituents, revealing unique information on the mechanisms of strong-field ionization and dissociation.
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spatiotemporal imaging of ultrafast molecular motion collapse and revival of the d 2 nuclear Wave Packet
Physical Review Letters, 2006Co-Authors: Th Ergler, Artem Rudenko, B Feuerstein, K Zrost, C D Schroter, R Moshammer, J UllrichAbstract:We report on a real-time imaging of the ultrafast $\mathrm{D}_{2}{}^{+}$ rovibrational nuclear Wave-Packet motion performed using a combination of a pump-probe setup with 7 fs laser pulses and a ``reaction-microscope'' spectrometer. We observe fast dephasing (collapse) of the vibrational Wave Packet and its subsequent revival and prove rotational excitation in ultrashort laser pulses. Channel-selective Fourier analysis of the Wave Packet's long-term ($\ensuremath{\sim}3000\text{ }\text{ }\mathrm{fs}$) evolution allows us to resolve its individual constituents, revealing unique information on the mechanisms of strong-field ionization and dissociation.
Christoph H Keitel - One of the best experts on this subject based on the ideXlab platform.
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photoemission of a single electron Wave Packet in a strong laser field
Physical Review Letters, 2008Co-Authors: Justin Peatross, Carsten Muller, Karen Zaven Hatsagortsyan, Christoph H KeitelAbstract:The radiation emitted by a single-electron Wave Packet in an intense laser field is considered. A relation between the exact quantum formulation and its classical counterpart is established via the electron's Wigner function. In particular, we show that the Wave Packet, even when it spreads to the scale of the Wavelength of the driving laser field, cannot be treated as an extended classical charge distribution, but rather behaves as a pointlike emitter carrying information on its initial quantum state. We outline an experimental setup dedicated to put this conclusion to the test.
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electron Wave Packet dynamics in a relativistic electromagnetic field 3 d analytical approximation
Optics Express, 2007Co-Authors: Justin Peatross, Carsten H G Muller, Christoph H KeitelAbstract:A solution to the Klein Gordon equation for a laser-driven electron is constructed from a superposition of Volkov states. The time-and space-dependent three-dimensional superposition integral can be evaluated analytically for an initial Gaussian momentum distribution when the expression for relativistic energy is expanded in a Taylor series over the scaled initial momenta. The solution preserves many complicated Wave-Packet dynamics in a strong field, including so-called Wave-Packet shearing and the formation of multiple peaks when the Wave Packet spreads to the scale of the driving-field Wavelength. The range of applicability of the solution applies to much of the parameter space accessible by current intense ultra-short laser systems.
Justin Peatross - One of the best experts on this subject based on the ideXlab platform.
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scattering of intense laser radiation by a single electron Wave Packet
Physical Review A, 2011Co-Authors: John Corson, Justin Peatross, Carsten Muller, Karen Zaven HatsagortsyanAbstract:A quantum theoretical description of photoemission by a single laser-driven electron Wave Packet is presented. Energy-momentum conservation ensures that the partial emissions from individual momentum components of the electron Wave Packet do not interfere when the driving field is unidirectional. In other words, light scattering by an electron Packet is independent of the phases of the pure momentum states comprising the Packet; the size of the electron Wave Packet does not matter. This result holds also in the case of high-intensity multiphoton scattering. Our analysis is first presented in the QED framework. Since QED permits the second-quantized entangled electron-photon final state to be projected onto pure plane-Wave states, the Born probability interpretation requires these projections to be first squared and then summed to find an overall probability of a scattering event. The QED treatment indicates how a semiclassical framework can be developed to recover the key features of the correct result.
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photoemission of a single electron Wave Packet in a strong laser field
Physical Review Letters, 2008Co-Authors: Justin Peatross, Carsten Muller, Karen Zaven Hatsagortsyan, Christoph H KeitelAbstract:The radiation emitted by a single-electron Wave Packet in an intense laser field is considered. A relation between the exact quantum formulation and its classical counterpart is established via the electron's Wigner function. In particular, we show that the Wave Packet, even when it spreads to the scale of the Wavelength of the driving laser field, cannot be treated as an extended classical charge distribution, but rather behaves as a pointlike emitter carrying information on its initial quantum state. We outline an experimental setup dedicated to put this conclusion to the test.
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electron Wave Packet dynamics in a relativistic electromagnetic field 3 d analytical approximation
Optics Express, 2007Co-Authors: Justin Peatross, Carsten H G Muller, Christoph H KeitelAbstract:A solution to the Klein Gordon equation for a laser-driven electron is constructed from a superposition of Volkov states. The time-and space-dependent three-dimensional superposition integral can be evaluated analytically for an initial Gaussian momentum distribution when the expression for relativistic energy is expanded in a Taylor series over the scaled initial momenta. The solution preserves many complicated Wave-Packet dynamics in a strong field, including so-called Wave-Packet shearing and the formation of multiple peaks when the Wave Packet spreads to the scale of the driving-field Wavelength. The range of applicability of the solution applies to much of the parameter space accessible by current intense ultra-short laser systems.
