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Full-Text Articles in Physical Sciences and Mathematics
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.
Laser Channeling Of Bethe-Heitler Pairs, Erik Lotstedt, Ulrich D. Jentschura, Christoph H. Keitel
Laser Channeling Of Bethe-Heitler Pairs, Erik Lotstedt, Ulrich D. Jentschura, Christoph H. Keitel
Physics Faculty Research & Creative Works
Electron-positron pair creation is analyzed for an arrangement involving three external fields: a high-frequency gamma photon, the Coulomb field of a nucleus, and a strong laser wave. The frequency of the incoming gamma photon is assumed to be larger than the threshold for pair production in the absence of a laser, and the peak electric field of the laser is assumed to be much weaker than Schwinger's critical field. The total number of pairs produced is found to be essentially unchanged by the laser field, while the differential cross section is drastically modified. We show that the laser can channel …
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 …
Long-Time Electron Spin Storage Via Dynamical Suppression Of Hyperfine-Induced Decoherence In A Quantum Dot, Wenxian Zhang, N. P. Konstantinidis, V. V. Dobrovitski, B. N. Harmon, Lea F. Santos, Lorenza Viola
Long-Time Electron Spin Storage Via Dynamical Suppression Of Hyperfine-Induced Decoherence In A Quantum Dot, Wenxian Zhang, N. P. Konstantinidis, V. V. Dobrovitski, B. N. Harmon, Lea F. Santos, Lorenza Viola
Dartmouth Scholarship
The coherence time of an electron spin decohered by the nuclear spin environment in a quantum dot can be substantially increased by subjecting the electron to suitable dynamical decoupling sequences. We analyze the performance of high-level decoupling protocols by using a combination of analytical and exact numerical methods, and by paying special attention to the regimes of large interpulse delays and long-time dynamics, which are outside the reach of standard average Hamiltonian theory descriptions. We demonstrate that dynamical decoupling can remain efficient far beyond its formal domain of applicability, and find that a protocol exploiting concatenated design provides best performance …
Potential For Ultrafast Dynamic Chemical Imaging With Few-Cycle Infrared Lasers, Toru Morishita, Anh-Thu Le, Zhangjin Chen, C. D. Lin
Potential For Ultrafast Dynamic Chemical Imaging With Few-Cycle Infrared Lasers, Toru Morishita, Anh-Thu Le, Zhangjin Chen, C. D. Lin
Physics Faculty Research & Creative Works
We studied the photoelectron spectra generated by an intense few cycle infrared laser pulse. By focusing on the angular distributions of the back rescattered high energy photoelectrons, we show that accurate differential elastic scattering cross-sections of the target ion by free electrons can be extracted. Since the incident direction and the energy of the free electrons can be easily changed by manipulating the laser's polarization, intensity and wavelength, these extracted elastic scattering cross-sections, in combination with more advanced inversion algorithms, may be used to reconstruct the effective single-scattering potential of the molecule, thus opening up the possibility of using few-cycle …
Isotope Shift In The Dielectronic Recombination Of Three-Electron ANd⁵⁷⁺, Carsten Brandau, Ch Kozhuharov, Zoltan Harman, Alfred K. Muller, Stefan Schippers, S. Kozhedub, Dietrich Bernhardt, Stefan Bohm, J. Jacobi, Eric W. Schmidt, Paul H. Mokler, Fritz J. Bosch, Heinz Jurgen Kluge, Th H. Stohlker, Klaus Beckert, P. Beller, Fritz Nolden, Markus Steck, Alexandre Gumberidze, Regina Reuschl, Uwe Spillmann, Fred John Currell, I. I. Tupitsyn, Vladimir M. Shabaev, Ulrich D. Jentschura
Isotope Shift In The Dielectronic Recombination Of Three-Electron ANd⁵⁷⁺, Carsten Brandau, Ch Kozhuharov, Zoltan Harman, Alfred K. Muller, Stefan Schippers, S. Kozhedub, Dietrich Bernhardt, Stefan Bohm, J. Jacobi, Eric W. Schmidt, Paul H. Mokler, Fritz J. Bosch, Heinz Jurgen Kluge, Th H. Stohlker, Klaus Beckert, P. Beller, Fritz Nolden, Markus Steck, Alexandre Gumberidze, Regina Reuschl, Uwe Spillmann, Fred John Currell, I. I. Tupitsyn, Vladimir M. Shabaev, Ulrich D. Jentschura
Physics Faculty Research & Creative Works
Isotope shifts in dielectronic recombination spectra were studied for Li-like ANd57+ ions with A = 142 and A = 150. From the displacement of resonance positions energy shifts δE142 150(2s-2p1/2) = 40.2(3)(6) meV [(stat)(sys)] and δE142 150(2s - 2p3/2) = 42.3(12)(20)meV of 2s - 2pj transitions were deduced. An evaluation of these values within a full QED treatment yields a change in the mean-square charge radius of 142 150δ⟨ r2⟩ = -1.36(1)(3) fm2. The approach is conceptually new and combines the advantage of a …