Laser-assisted inelastic scattering of electrons by helium atoms

Agueny, Hicham; Makhoute, A.; Dubois, Alain; Ajana, Imane; Rahali, G.

doi:10.1103/physreva.92.013423

Cited by 12 publications

(18 citation statements)

References 34 publications

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“…As experiment showing a zero at = 0. The double peak structure in the experimental data can be attributed to Fraunhofer diffraction effects [1][2][3][4][5][6] with the minimum in the experiment occurring at the predicted first dark band of a single slit diffraction pattern. These features have been accurately reproduced with models based on semiclassical atomic or molecular orbital expansions [2,3,5,6].…”

Section: Resultsmentioning

confidence: 99%

“…The double peak structure in the experimental data can be attributed to Fraunhofer diffraction effects [1][2][3][4][5][6] with the minimum in the experiment occurring at the predicted first dark band of a single slit diffraction pattern. These features have been accurately reproduced with models based on semiclassical atomic or molecular orbital expansions [2,3,5,6]. In these models, a direct comparison between the mathematical expression for the differential cross section and that of the light intensity in classical single slit diffraction shows nearly identical functional forms [3].…”

Section: Resultsmentioning

confidence: 99%

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Quantum mechanical potentials and inactive electron effects in charge exchange collisions

Harris¹,

Plumadore²

2019

J. Phys. B: At. Mol. Opt. Phys.

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Scattering angle differential cross sections for the He + + He single electron capture process are studied using plane wave Born approximation models for projectile energies between 30 keV and 1.89 MeV. Within this simplistic framework, we study the effects of the frozen core approximation by performing a full 5-Body calculation that explicitly includes all particles in the collision and comparing it with a single bound state model that neglects the bound electron in the projectile and a double bound state model that neglects the inactive electron in the target atom.Results are compared with experiment and we show that inclusion of the inactive electron in the perturbation potential is more important than inclusion in the wave functions. We also introduce a semi-quantum mechanical perturbation potential that treats the atomic electrons as a quantum mechanical electron cloud rather than point particles. The semi-quantum mechanical perturbation removes the deep, unphysical minimum that exists in cross sections calculated with Born-type models, but also has the effect of greatly reducing the magnitude of the small scattering angle cross sections.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Quantum mechanical potentials and inactive electron effects in charge exchange collisions

Harris¹,

Plumadore²

2019

J. Phys. B: At. Mol. Opt. Phys.

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“…At the end of the interaction t = t f , we calculate the 2D-momentum distribution of the photoelectron from the Fourier transform of the spatial ionization wave function ψ ioniz 50, 51 . The latter is evaluated using a projection technique 52,53 . In this technique, we consider orthogonal projection operatorsP andQ, such that Q = 1 −P = 1 − N ∑ n |ψ n ψ n |,…”

Section: Methodsmentioning

confidence: 99%

Quantum control and characterization of ultrafast ionization with orthogonal two-color laser pulses

Agueny

2020

Sci Rep

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We study ultrafast ionization dynamics using orthogonally polarized two-color (OTC) laser pulses involving the resonant "first plus second" (ω + 2ω) scheme. The scheme is illustrated by numerical simulations of the time-dependent Schrödinger equation and recording the photoelectron momentum distribution. On the basis of the simulations of this resonant ionization, we identify signatures of the dynamic Autler-Townes effect and dynamic interference, in which their characterization is not possible in spectral domain. Taking advantage of the OTC scheme we show that these dynamical effects, which occur at the same time scale, can be characterized in momentum space by controlling the spatial quantum interference. In particular, we show that with the use of this control scheme, one can tailor the properties of the control pulse to lead to enhancement of the ionization rate through the Autler-Townes effect without affecting the dynamic interference. This enhancement is shown to result from constructive interferences between partial photoelectron waves having opposite-parity, and found to manifest by symmetry-breaking of the momentum distribution. The scenario is investigated for a prototype of a hydrogen atom and is broadly applicable to other systems. Our findings may have applications for photoelectron interferometers to control the electron dynamics in time and space, and for accurate temporal characterization of attosecond pulses.

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“…Although this approximation is valid only at high electron energies, it has been shown to provide new insights into the inelastic scattering process assisted by laser fields, in particular in the regime where the perturbation theory for laser-atom interactions breaks down. For instance, it has been shown that the computed differential cross-sections encode information about the avoided crossing induced by a resonant laser field [23], which in turn can be controlled by varying the properties of the laser fields, as well as those of the monoenergetic electron beam [24,25]. At a low electron energy, the second-order Born approximation is required in order to take into account the additional effects such as the exchange effects [26,27], which are necessary for the precise comparison with an experiment.…”

Section: Introductionmentioning

confidence: 99%

Simultaneous Excitation of Helium by Means of an Electron and a Photon: A Joined Experimental and Theoretical Study

Ajana

Nehari

Khalil

et al. 2021

Atoms

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We report on a joined experimental and theoretical study of differential cross-sections resulting from inelastic scattering of a monoenergetic electron by helium atoms in the presence of an intense carbon dioxide laser. In particular, we measured the signals of the scattered electrons during the simultaneous electron–photon excitation of He 21P state for the first three microseconds of the laser pulse. The signals were measured for an incident electron energy of 45 eV and showed a structure that emerged at small scattering angles. The latter was found to be sensitive to the nature of the transferred photons, as well as the intensity of the laser field. The experimental findings were supported by quantum calculations based on the second-order Born approximation in which the correlated electron–electron interactions were taken into account.

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Laser-assisted inelastic scattering of electrons by helium atoms

Cited by 12 publications

References 34 publications

Quantum mechanical potentials and inactive electron effects in charge exchange collisions

Quantum mechanical potentials and inactive electron effects in charge exchange collisions

Quantum control and characterization of ultrafast ionization with orthogonal two-color laser pulses

Simultaneous Excitation of Helium by Means of an Electron and a Photon: A Joined Experimental and Theoretical Study

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