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Physics Faculty Research & Creative Works

Atoms

2015

Articles 1 - 5 of 5

Full-Text Articles in Physical Sciences and Mathematics

Low-Energy (E₀ = 65 Ev) Electron-Impact Ionization Of Neon: Internormalized Triple-Differentical Cross Sections In 3d Kinematics, Xueguang Ren, Sadek M. Amami, Oleg I. Zatsarinny, Thomas Pfluger, Marvin Weyland, Woon Yong Baek, Hans Rabus, Klaus Bartschat, Don H. Madison, Alexander Dorn Sep 2015

Low-Energy (E₀ = 65 Ev) Electron-Impact Ionization Of Neon: Internormalized Triple-Differentical Cross Sections In 3d Kinematics, Xueguang Ren, Sadek M. Amami, Oleg I. Zatsarinny, Thomas Pfluger, Marvin Weyland, Woon Yong Baek, Hans Rabus, Klaus Bartschat, Don H. Madison, Alexander Dorn

Physics Faculty Research & Creative Works

We present a combined experimental and theoretical study on the low-energy (E0 = 65 eV) electron- impact ionization of neon. The experimental data are compared to predictions from a hybrid second-order distorted-wave Born plus R-matrix approach (DWB2-RM), the distorted-wave Born approximation with inclusion of post-collision interaction (DWBA-PCI), a three-body distorted-wave approach (3DW), and a B-spline R-matrix (BSR) with pseudostates approach. Excellent agreement is found between experiment and the 3DW and BSR theories. The importance of PCI effects is clearly visible in this low-energy electron-impact ionization process.


Evidence For Unnatural-Parity Contributions To Electron-Impact Ionization Of Laser-Aligned Atoms, G. S. J. Armstrong, J. Colgan, M. S. Pindzola, S. Amami, Don H. Madison, J. Pursehouse, K. L. Nixon, A. J. Murray Sep 2015

Evidence For Unnatural-Parity Contributions To Electron-Impact Ionization Of Laser-Aligned Atoms, G. S. J. Armstrong, J. Colgan, M. S. Pindzola, S. Amami, Don H. Madison, J. Pursehouse, K. L. Nixon, A. J. Murray

Physics Faculty Research & Creative Works

Recent measurements have examined the electron-impact ionization of excited-state laser-aligned Mg atoms. In this work we show that the ionization cross section arising from the geometry where the aligned atom is perpendicular to the scattering plane directly probes the unnatural parity contributions to the ionization amplitude. The contributions from natural parity partial waves cancel exactly in this geometry. Our calculations resolve the discrepancy between the nonzero measured cross sections in this plane and the zero cross section predicted by distorted-wave approaches. We demonstrate that this is a general feature of ionization from p-state targets by additional studies of ionization from ...


Coplanar Asymmetric Angles And Symmetric Energy Sharing Triple Differential Cross Sections For 200 Ev Electron-Impact Ionization Of Ar (3p), Zehra Nur Ozer, Sadek M. Amami, Onur Varol, Murat Yavuz, Mevlut Dogan, Don H. Madison Sep 2015

Coplanar Asymmetric Angles And Symmetric Energy Sharing Triple Differential Cross Sections For 200 Ev Electron-Impact Ionization Of Ar (3p), Zehra Nur Ozer, Sadek M. Amami, Onur Varol, Murat Yavuz, Mevlut Dogan, Don H. Madison

Physics Faculty Research & Creative Works

We have measured triple differential cross sections (TDCSs) for electron-impact ionization of the 3p shell of Ar at 200 eV incident electron energy. The experiments have been performed in coplanar asymmetric energy sharing geometry. The experimental results are compared with the theoretical models of three body distorted wave (3DW) and distorted wave Born approximation (DWBA).


One-Loop Dominance In The Imaginary Part Of The Polarizability: Application To Blackbody And Noncontact Van Der Waals Friction, Ulrich D. Jentschura, Grzegorz Lach, Maarten Dekieviet, Krzysztof Pachucki Jan 2015

One-Loop Dominance In The Imaginary Part Of The Polarizability: Application To Blackbody And Noncontact Van Der Waals Friction, Ulrich D. Jentschura, Grzegorz Lach, Maarten Dekieviet, Krzysztof Pachucki

Physics Faculty Research & Creative Works

Phenomenologically important quantum dissipative processes include blackbody friction (an atom absorbs counterpropagating blueshifted photons and spontaneously emits them in all directions, losing kinetic energy) and noncontact van der Waals friction (in the vicinity of a dielectric surface, the mirror charges of the constituent particles inside the surface experience drag, slowing the atom). The theoretical predictions for these processes are modified upon a rigorous quantum electrodynamic treatment, which shows that the one-loop "correction" yields the dominant contribution to the off-resonant, gauge-invariant, imaginary part of the atom's polarizability at room temperature, for typical atom-surface interactions. The tree-level contribution to the polarizability ...


Long-Range Atom-Wall Interactions And Mixing Terms: Metastable Hydrogen, Ulrich D. Jentschura Jan 2015

Long-Range Atom-Wall Interactions And Mixing Terms: Metastable Hydrogen, Ulrich D. Jentschura

Physics Faculty Research & Creative Works

We investigate the interaction of metastable 2S hydrogen atoms with a perfectly conducting wall, including parity-breaking S-P mixing terms (with full account of retardation). The neighboring 2P1/2 and 2P3/2 levels are found to have a profound effect on the transition from the short-range, nonrelativistic regime, to the retarded form of the Casimir-Polder interaction. The corresponding P state admixtures to the metastable 2S state are calculated. We find the long-range asymptotics of the retarded Casimir-Polder potentials and mixing amplitudes for general excited states, including a fully quantum electrodynamic treatment of the dipole-quadrupole mixing term. The decay width ...