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Articles 1 - 8 of 8
Full-Text Articles in Physical Sciences and Mathematics
Recurrence Spectroscopy Of A Time-Dependent System: A Rydberg Atom In An Oscillating Field, Neal Spellmeyer, Daniel Kleppner, M. R. Haggerty, V. Kondratovich, John B. Delos, J. Gao
Recurrence Spectroscopy Of A Time-Dependent System: A Rydberg Atom In An Oscillating Field, Neal Spellmeyer, Daniel Kleppner, M. R. Haggerty, V. Kondratovich, John B. Delos, J. Gao
Arts & Sciences Articles
We report the results of an experimental and theoretical investigation of the recurrence spectra of Rydberg atoms in a static plus weak oscillating electric field. Experiments reveal the systematic weakening of orbits in a recurrence spectrum as the oscillating field strength and frequency are changed. We describe a generalization of closed orbit theory to time-dependent systems and show that it provides a qualitative and quantitative description of the phenomena.
Semiclassical Formula For Oscillator Strengths In Atomic Spectra, V. Kondratovich, John B. Delos
Semiclassical Formula For Oscillator Strengths In Atomic Spectra, V. Kondratovich, John B. Delos
Arts & Sciences Articles
A simple semiclassical formula is given for the oscillator strengths of high Rydberg states of a hydrogen atom in an electric field. The oscillator strength of a state is proportional to the square of the function representing the quantum angular distribution of outgoing waves, evaluated at the classical angle of ejection from the atom that sends the electron into a semiclassically quantized eigentrajectory. The formula gives an interpretation of the envelopes of Stark manifolds in photoabsorption spectra; it is in good agreement with quantum calculations. The formula may also be used for other integrable or near-integrable systems.
Quantum Manifestations Of Bifurcations Of Closed Orbits In The Photodetachment Cross Section Of H- In Parallel Fields, Aaron D. Peters, Charles Jaffé, J. Gao, John B. Delos
Quantum Manifestations Of Bifurcations Of Closed Orbits In The Photodetachment Cross Section Of H- In Parallel Fields, Aaron D. Peters, Charles Jaffé, J. Gao, John B. Delos
Arts & Sciences Articles
In the preceding paper, we showed that the semiclassical approximation diverges at a bifurcation, and that this divergence coincides with the passage of a focused cusp through the origin. Here we obtain a wave function in the vicinity of this cusp, and we use that wave function to eliminate the divergences in the photodetachment cross section. To describe the focused cusp, we first discuss the wave function of an ordinary two-dimensional (nonfocused) cusp. This wave function is known as a Pearcey function, and it has been studied extensively. Then we show how the formulas that lead to the Pearcey function …
Quantum Manifestations Of Bifurcations Of Closed Orbits In The Photoabsorption Spectra Of Atoms In Electric Fields, J. Gao, John B. Delos
Quantum Manifestations Of Bifurcations Of Closed Orbits In The Photoabsorption Spectra Of Atoms In Electric Fields, J. Gao, John B. Delos
Arts & Sciences Articles
The methods developed in the preceding paper (paper II) are used to construct a wave function near a bifurcation of classical orbits of an atomic electron in an electric field. A formula for the recurrence strength near the bifurcation is derived and compared with experimental measurements.
Closed-Orbit Theory And The Photodetachment Cross Section Of H- In Parallel Electric And Magnetic Fields, Aaron D. Peters, Charles Jaffé, J. B. Delos
Closed-Orbit Theory And The Photodetachment Cross Section Of H- In Parallel Electric And Magnetic Fields, Aaron D. Peters, Charles Jaffé, J. B. Delos
Arts & Sciences Articles
In this paper we obtain a simple analytic formula for the photodetachment cross section of H− in parallel electric and magnetic fields. The three-dimensional semiclassical approximation predicts oscillations in the spectrum and correlates these oscillations with closed classical orbits. The cylindrical symmetry of the Hamiltonian produces some interesting effects. In particular, at boundary energies the semiclassical approximation fails as a focused cusp approaches the origin.
Symmetry Breaking In Crossed Magnetic And Electric Fields, C. Neumann, R. Ubert, S. Freund, Et Al., John B. Delos
Symmetry Breaking In Crossed Magnetic And Electric Fields, C. Neumann, R. Ubert, S. Freund, Et Al., John B. Delos
Arts & Sciences Articles
We present the first observations of cylindrical symmetry breaking in highly excited diamagnetic hydrogen with a small crossed electric field, and we give a semiclassical interpretation of this effect. As the small perpendicular electric field is added, the recurrence strengths of closed orbits decrease smoothly to a minimum, and revive again. This phenomenon, caused by interference among the electron waves that return to the nucleus, can be computed from the azimuthal dependence of the classical closed orbits.
Semiclassical Picture Of Collision-Induced Λ-Doublet Transitions In Diatomic Molecules, Laurie J. Kovalenko, J. B. Delos
Semiclassical Picture Of Collision-Induced Λ-Doublet Transitions In Diatomic Molecules, Laurie J. Kovalenko, J. B. Delos
Arts & Sciences Articles
We investigate collision-induced Λ-doublet transitions in a system similar to NO+Ar, based on a semiclassical model in which nuclear motion is treated classically and electronic motion quantum mechanically. We present a picture of this process by monitoring〈Λ〉, the expectation value of the projection of electronic orbital-angular momentum onto the molecular NO axis, over the duration of the collision. In a typical collision, the interaction with Ar would cause the electronic orbital-angular momentum to precess about the rotating NO–Ar vector. However, since this angular momentum is locked tightly to the diatomic axis, it is restricted to oscillation along this axis. This …
Semiclassical Model Of Λ-Doublet States In Diatomic Molecules, Laurie J. Kovalenko, John B. Delos
Semiclassical Model Of Λ-Doublet States In Diatomic Molecules, Laurie J. Kovalenko, John B. Delos
Arts & Sciences Articles
An intuitive picture of Λ-doubling in diatomic molecules is presented using a semiclassical theory. A common view of Λ-doubling as arising from electrons “lagging” behind the rotating internuclear axis is shown to be misleading; rather, the eigenfunctions are symmetric about the molecular axes and can be expressed as a superposition of pure nonrotating orbitals and travelling waves. These results are shown to be consistent with a full quantum treatment. We also examine, for the first time, time-dependent states, by monitoring expectation values of electronic- and nuclear-angular momenta. For low rotation frequency, the expectation value of the electronic-angular momentum locks onto …