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Semiclassical Methods in Atomic and ...

Ambalampitiya, Harindranath B.

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Semiclassical Methods in Atomic and Molecular Physics.

Record Type:	Electronic resources : Monograph/item
Title/Author:	Semiclassical Methods in Atomic and Molecular Physics./
Author:	Ambalampitiya, Harindranath B.
Published:	Ann Arbor : ProQuest Dissertations & Theses, : 2021,
Description:	174 p.
Notes:	Source: Dissertations Abstracts International, Volume: 82-10, Section: B.
Contained By:	Dissertations Abstracts International82-10B.
Subject:	Molecular physics. -
Online resource:	https://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=28418425
ISBN:	9798728229544

Semiclassical Methods in Atomic and Molecular Physics.
Ambalampitiya, Harindranath B.

Semiclassical Methods in Atomic and Molecular Physics. - Ann Arbor : ProQuest Dissertations & Theses, 2021 - 174 p.

Source: Dissertations Abstracts International, Volume: 82-10, Section: B.

Thesis (Ph.D.)--The University of Nebraska - Lincoln, 2021.

This item must not be sold to any third party vendors.

Semiclassical approximation which is the marriage of classical and quantum mechanics can be applied to a large variety of problems in quantum physics. In addition to being a highly intuitive approach, often the semiclassical results can be as accurate as the exact quantum calculations. This dissertation explores in detail and comparatively the application of classical, semiclassical, and quantum theories to some selected electron-ion and electron-molecule interactions. We first study classically the laser-assisted spontaneous electron bremsstrahlung in a combined Coulomb and laser (ac) fields. Due to chaotic scattering, the radiation probability as a function of the impact parameter and the constant phase of the laser field exhibits fractal structures. At low incident electron kinetic energy, the Coulomb focusing leads to a substantial extension of the range of impact parameters enhancing the bremsstrahlung cross section as compared to the pure Coulomb case. Next, we implement the Classical trajectory Monte Carlo (CTMC) method to compute charge-transfer cross section in low-energy positronium-proton collisions. The CTMC approach gives accurate and reliable cross sections having the same scaling law as obtained by exact quantum calculations. However, we observe a suppression in the quantum cross section which is mainly due to the low-impact parameter behavior of the probabilities governed by the quantum uncertainty principle. By treating photodetachment in combined high-frequency laser and low-frequency fields, we investigate semiclassically the temporal and spatial interference structure in the electron current density. The time-dependent Green's function is used for calculation of electron flux on a detector. The caustic divergences in the electron flux are removed by using the uniform Airy approximation. Finally, we treat the dissociative electron attachment (DEA) to polyatomic molecules by developing the multi-mode nonlocal theory of DEA. The nonlocal theory is complemented by a semiclassical approach. With the inclusion of two vibrational modes, we demonstrate the application of the new theory to a generic molecule of the type CY3X, where Y denotes the H or F atom and X denotes the halogen atom.

ISBN: 9798728229544Subjects--Topical Terms:

3174737
Molecular physics.
Subjects--Index Terms:

Antihydrogen

Semiclassical Methods in Atomic and Molecular Physics.
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245 1 0 $a Semiclassical Methods in Atomic and Molecular Physics.
260 1 $a Ann Arbor : $b ProQuest Dissertations & Theses, $c 2021
300 $a 174 p.
500 $a Source: Dissertations Abstracts International, Volume: 82-10, Section: B.
500 $a Advisor: Fabrikant, Ilya I.
502 $a Thesis (Ph.D.)--The University of Nebraska - Lincoln, 2021.
506 $a This item must not be sold to any third party vendors.
520 $a Semiclassical approximation which is the marriage of classical and quantum mechanics can be applied to a large variety of problems in quantum physics. In addition to being a highly intuitive approach, often the semiclassical results can be as accurate as the exact quantum calculations. This dissertation explores in detail and comparatively the application of classical, semiclassical, and quantum theories to some selected electron-ion and electron-molecule interactions. We first study classically the laser-assisted spontaneous electron bremsstrahlung in a combined Coulomb and laser (ac) fields. Due to chaotic scattering, the radiation probability as a function of the impact parameter and the constant phase of the laser field exhibits fractal structures. At low incident electron kinetic energy, the Coulomb focusing leads to a substantial extension of the range of impact parameters enhancing the bremsstrahlung cross section as compared to the pure Coulomb case. Next, we implement the Classical trajectory Monte Carlo (CTMC) method to compute charge-transfer cross section in low-energy positronium-proton collisions. The CTMC approach gives accurate and reliable cross sections having the same scaling law as obtained by exact quantum calculations. However, we observe a suppression in the quantum cross section which is mainly due to the low-impact parameter behavior of the probabilities governed by the quantum uncertainty principle. By treating photodetachment in combined high-frequency laser and low-frequency fields, we investigate semiclassically the temporal and spatial interference structure in the electron current density. The time-dependent Green's function is used for calculation of electron flux on a detector. The caustic divergences in the electron flux are removed by using the uniform Airy approximation. Finally, we treat the dissociative electron attachment (DEA) to polyatomic molecules by developing the multi-mode nonlocal theory of DEA. The nonlocal theory is complemented by a semiclassical approach. With the inclusion of two vibrational modes, we demonstrate the application of the new theory to a generic molecule of the type CY3X, where Y denotes the H or F atom and X denotes the halogen atom.
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650 4 $a Quantum physics. $3 726746
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650 4 $a Atomic physics. $3 3173870
653 $a Antihydrogen
653 $a Dissociative Electron Attachment
653 $a Laser-assisted processes
653 $a Nonlocal theory
653 $a Positronium
653 $a Semiclassical approximation
653 $a Polyatomic molecules
653 $a Electron current density
690 $a 0753
690 $a 0599
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710 2 $a The University of Nebraska - Lincoln. $b Physics & Astronomy. $3 1064692
773 0 $t Dissertations Abstracts International $g 82-10B.
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791 $a Ph.D.
792 $a 2021
793 $a English
856 4 0 $u https://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=28418425