Showing papers in "Physical Review in 1992"
Journal Article•
TL;DR: In this article, X-ray-absorption near-edge structure (XANES) data were collected for Zn in sphalerite (ZnS), and for Cu and Fe in chalcopyrite (${\mathrm{CuFeS}}_{2}$), where all three cations are in nearly identical coordination environments.
Abstract: X-ray-absorption near-edge structure (XANES) data were collected for Zn in sphalerite (ZnS), and for Cu and Fe in chalcopyrite (${\mathrm{CuFeS}}_{2}$), where all three cations are in nearly identical coordination environments. The data have similar features, except near the edge, where the edge maximum decreases in amplitude, while a pre-edge feature appears and increases in amplitude from Zn to Cu to Fe. The pre-edge feature was previously assigned to a 1s-to-3d atomic transition for Cu and Fe in the chalcopyrite structure. XANES calculations were performed for all three edges. The multiple- and single-scattering contributions to the calculated edge spectra were scaled down to better fit the experimental data. The conclusions from the calculations indicate that the pre-edge feature in the experimental Cu- and Fe-edge data for chalcopyrite can be due to interference effects from the atomic structure surrounding the absorber, but cannot exclude the possibility that the pre-edge feature is due to atomic bound-state transitions of the absorber.
18 citations
Journal Article•
TL;DR: In this article, the role of classical resonances in quantum systems subjected to a periodic external force was studied and it was demonstrated that classical invariant vortex tubes determine the structure of Floquet states captured by resonances.
Abstract: We study the role of classical resonances in quantum systems subjected to a periodic external force. It is demonstrated that classical invariant vortex tubes determine the structure of Floquet states ‘‘captured’’ by resonances in the classical phase space. In addition, resonance quantum numbers are introduced. The analysis of simple model calculations leads to a qualitative description of nonperturbative phenomena relevant for the interaction of atoms or molecules with strong, short laser pulses.
15 citations
Journal Article•
3 citations
Journal Article•
TL;DR: A simple picture of resonant trapping of classical states and its semiclassical analog is developed and its relevance is illustrated by numerical analysis and by pointing out its verification in microwave excitation of highly excited hydrogen.
Abstract: We discuss the role of separatrix crossing in a classical Hamiltonian system for a description of transitions in the corresponding quantum system. We develop a simple picture of resonant trapping of classical states and its semiclassical analog. Its relevance is illustrated by numerical analysis and by pointing out its verification in microwave excitation of highly excited hydrogen.
Journal Article•
TL;DR: In this paper, the theoretical treatment of ultrafast time-resolved hole burning has been studied for nonoverlapping and overlapping pulses as well as the effects of the temperature are included in the theory.
Abstract: In this paper, we report the theoretical treatment of ultrafast time-resolved hole burning. The description is valid for nonoverlapping and overlapping pulses as well. Also the effects of the temperature are included in the theory. The influence of the various contributions to the transient hole-burning spectrum corresponding to the level population, pump polarization coupling, and perturbed free-induction-decay terms is stressed.