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Full-Text Articles in Physics
Differential Cross Sections For The Ionization Of Oriented H₂ Molecules By Electron Impact, James Colgan, Michael S. Pindzola, Francis J. Robicheaux, Christian V. Kaiser, Andrew James Murray, Don H. Madison
Differential Cross Sections For The Ionization Of Oriented H₂ Molecules By Electron Impact, James Colgan, Michael S. Pindzola, Francis J. Robicheaux, Christian V. Kaiser, Andrew James Murray, Don H. Madison
Physics Faculty Research & Creative Works
A nonperturbative close-coupling technique is used to calculate differential cross sections for the electron-impact ionization of H2 at an energy of 35.4 eV. Our approach allows cross sections for any orientation of the molecule with respect to the incident electron beam to be analyzed. New features in the resulting cross sections are found compared with the case where the molecular orientation is averaged, and also with cross sections for He at equivalent electron kinematics. When averaged over all possible molecular orientations, good agreement is found with recent experimental results.
Reexamining Blackbody Shifts For Hydrogenlike Ions, Ulrich D. Jentschura, Martin K. Haas
Reexamining Blackbody Shifts For Hydrogenlike Ions, Ulrich D. Jentschura, Martin K. Haas
Physics Faculty Research & Creative Works
We investigate blackbody-induced energy shifts for low-lying levels of atomic systems, with a special emphasis on transitions used in current and planned high-precision experiments on atomic hydrogen and ionized helium. Fine-structure- and Lamb-shift-induced blackbody shifts are found to increase with the square of the nuclear charge number, whereas blackbody shifts due to virtual transitions decrease with increasing nuclear charge as the fourth power of the nuclear charge. We also investigate the decay width acquired by the ground state of atomic hydrogen, due to interaction with blackbody photons. The corresponding width is due to an instability against excitation to higher excited …
Signature Of Ericson Fluctuations In Helium Inelastic Scattering Cross Sections Near The Double Ionization Threshold, Junliang Xu, Anh-Thu Le, Toru Morishita, C. D. Lin
Signature Of Ericson Fluctuations In Helium Inelastic Scattering Cross Sections Near The Double Ionization Threshold, Junliang Xu, Anh-Thu Le, Toru Morishita, C. D. Lin
Physics Faculty Research & Creative Works
We calculated the inelastic electron impact excitation cross sections of He⁺ by electrons for a model helium atom to examine the onset of the signature of quantum chaotic scattering in this simple system. We find Ericson fluctuations (EF) in the calculated inelastic scattering cross sections only when the impact energies lie within about 0.21 eV below the double ionization threshold. We also discuss the stringent requirements and the proper methods for analyzing the inelastic scattering cross sections in order to observe EF experimentally.
Double Ionization Of Helium By Ion Impact Analyzed Using Four-Body Dalitz Plots, M. F. Ciappina, Michael Schulz, T. Kirchner, Daniel Fischer, R. Moshammer, J. D. Ullrich
Double Ionization Of Helium By Ion Impact Analyzed Using Four-Body Dalitz Plots, M. F. Ciappina, Michael Schulz, T. Kirchner, Daniel Fischer, R. Moshammer, J. D. Ullrich
Physics Faculty Research & Creative Works
We have performed experimental and theoretical studies of double ionization of helium by 6 MeV proton impact using a recently developed tool, four-particle Dalitz plots [Schulz et al., J. Phys. B 22, 3091 (2007)] which enable the representation of multiple differential cross sections as a function of all four fragments in a single spectrum without loss of any part of the total cross section. As a result, the relative importance of the various interactions between the fragments can be studied in great detail. Comparisons of experimental data with theoretical first-order calculations and simulations for the higher-order (TS-2) process show that …
Alignment Of Heavy Few-Electron Ions Following Excitation By Relativistic Coulomb Collisions, Andrey S. Surzhykov, Ulrich D. Jentschura, Th H. Stohlker, Alexandre Gumberidze, Stephan Fritzsche
Alignment Of Heavy Few-Electron Ions Following Excitation By Relativistic Coulomb Collisions, Andrey S. Surzhykov, Ulrich D. Jentschura, Th H. Stohlker, Alexandre Gumberidze, Stephan Fritzsche
Physics Faculty Research & Creative Works
The Coulomb excitation of highly charged few-electron ions in relativistic collisions with protons and low- Z atoms is studied within the framework of first-order perturbation theory and the multiconfiguration Dirac-Fock method. Apart from the computation of the total excitation cross sections, a detailed theoretical analysis has been performed for the magnetic sublevel population of the residual ions. To describe this population, general expressions are derived for the alignment parameters of the excited states of the ions, taking into account the relativistic and many-electron effects. Calculations are performed for the K→L and K→M excitation of helium- and lithiumlike uranium ions and …
Projectile Angular-Differential Cross Sections For Transfer And Transfer Excitation In Proton Collisions With Helium, M. Zapukhlyak, T. Kirchner, Ahmad Hasan, B. Tooke, Michael Schulz
Projectile Angular-Differential Cross Sections For Transfer And Transfer Excitation In Proton Collisions With Helium, M. Zapukhlyak, T. Kirchner, Ahmad Hasan, B. Tooke, Michael Schulz
Physics Faculty Research & Creative Works
Projectile angular-differential cross sections for single-transfer and transfer excitation have been calculated with the two-center extension of the nonperturbative basis generator method for 5-200 keV proton-helium collisions. The calculations are based on the independent electron model, and the eikonal approximation has been used to extract angular-differential cross sections from impact-parameter-dependent transition amplitudes. The present results are compared with experimental and previous theoretical data where available. In particular, we consider the ratio of transfer excitation to single capture versus double excitation to single excitation at intermediate energies. An experimentally observed structure in this ratio at a scattering angle about 0.5 mrad …