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Full-Text Articles in Physics
Detecting Electron Motion In Atoms And Molecules, Hua-Chieh Shao, Anthony F. Starace
Detecting Electron Motion In Atoms And Molecules, Hua-Chieh Shao, Anthony F. Starace
Anthony F. Starace Publications
The detection of spatial and temporal electronic motion by scattering of subfemtosecond pulses of 10 keV electrons from coherent superpositions of electronic states of both H and T+2 is investigated. For the H atom, we predict changes in the diffraction images that reflect the time-dependent effective radius of the electronic charge density. For an aligned T+2 molecule, the diffraction image changes reflect the time-dependent localization or delocalization of the electronic charge density.
Unl Physicists Model Potential 4-D Imaging Technique, Tom Simons, Hua-Chieh Shao, Anthony F. Starace
Unl Physicists Model Potential 4-D Imaging Technique, Tom Simons, Hua-Chieh Shao, Anthony F. Starace
Anthony F. Starace Publications
A long-standing goal of science is to be able to understand how matter behaves at the atomic and subatomic level. How electrons rearrange when atoms or molecules come together is the essence of chemistry, and the ability to manipulate those rearrangements is the goal of the emerging sphere of nanotechnology. A fuller understanding could lead to enormous scientific and technological breakthroughs. Unfortunately, significant problems confront scientists and engineers in attacking the question. Not only are atoms and molecules very small, requiring highly specialized equipment to "see" them, everything at the atomic level happens very, very fast. For example, an electron …
Movies Of Electrons In Atoms, Michael Schirber, Hua-Chieh Shao, Anthony F. Starace
Movies Of Electrons In Atoms, Michael Schirber, Hua-Chieh Shao, Anthony F. Starace
Anthony F. Starace Publications
Physicists have long been able to snap atomic-scale pictures by shining a beam of electrons at a target, but filming the electronic structure of an atom as it changes in time is the next goal. A rapid "strobing" of electron pulses less than a millionth of a billionth of a second long should do the trick, according to a theoretical analysis in the 24 December Physical Review Letters. The authors demonstrate with computer simulations that ultrafast electron pulses could track the "breathing" state of an excited atom or the hopping of electrons between atoms in a molecule. Such movies open …
Potential Barrier Effects In Two-Photon Ionization Processes, Liang-Wen Pi, Anthony F. Starace
Potential Barrier Effects In Two-Photon Ionization Processes, Liang-Wen Pi, Anthony F. Starace
Anthony F. Starace Publications
Potential barriers in the effective radial potential experienced by a photoexcited electron are shown to result in dramatic, resonancelike effects in two-photon ionization processes. In a two-photon ionization process, such potential barriers may affect not only the final state of the electron (as in ordinary photoionization), but also the intermediate-state electron wave packet corresponding to the absorption of one photon. We illustrate these effects for the generalized two-photon cross sections for ionization of Ar and Xe within a single-active-electron, central-potential model.
Potential Barrier Effects In High-Order Harmonic Generation By Transition-Metal Ions, M. V. Frolov, N. L. Manakov, Anthony F. Starace
Potential Barrier Effects In High-Order Harmonic Generation By Transition-Metal Ions, M. V. Frolov, N. L. Manakov, Anthony F. Starace
Anthony F. Starace Publications
The experimental finding of significant enhancement or suppression of particular harmonics generated by the ionic component of laser-produced plasmas of transition-metal atoms is explained theoretically in terms of the standard three-step scenario for strong-field harmonic generation, taking into account the potential barrier effects that lead to a strong 3p → 3d electric dipole transition that dominates the photoionization cross sections of the outer subshells of those ions.