Electron capture from coherent elliptic Rydberg states

Day, J. C.; DePaola, B. D.; Ehrenreich, T.; Hansen, S. B.; Horsdal-Pedersen, E; Leontiev, Y.; Mogensen, K. S.

doi:10.1103/physreva.56.4700

Cited by 10 publications

(27 citation statements)

References 35 publications

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“…This distortion is quite regular, and reminds of a Stark effect. Indeed, a simple estimate confirms this: for Q=8, an electric field strength of 5V/cm (i.e., of the order of the fields applied to the collision region in the experiments [1]) is attained at approximately 10 5 a.u. This initial state effect might be reduced in the experiment by applying a strong field in the target region; however, this results also illuminates an inherent weakness of the CTMC-approach: the slow rise of the electric field may "in reality" induce adiabatic transitions between the many Rydberg states which would be populated differently in the classical calculation.…”

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confidence: 56%

“…The use of coherent elliptical Rydberg states in ion-atom collision studies (for recent papers on the subject cf. [1][2][3] and references therein) has not only aided the intuitive understanding of the interaction dynamics , it also illuminates the roles of the momentum and the spatial distributions of the target electron states. In classical terms, the momentum distribution can be widely varied simply by changing the eccentricity ε of the Rydberg ellipse without affecting the energy of the state.…”

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confidence: 99%

“…These investigations have so far been restricted to collisions with singly charged ions. Recently, however, it has become possible to employ such targets in studies involving multiply charged ions [1,4]. In another context (electron capture by multiply charged ion in the presence of an external magnetic field) we have found indications [5] that for increasing projectile charge Q the dis-tortion of the initial state increasingly dominates over the influence of different target electron distributions; we have therefore performed an exploratory study of such systems which is the topic of this Letter.…”

mentioning

confidence: 99%

“…We employ the classical trajectory Monte Carlo (CTMC) method which is quite useful in particular for the description of quantum mechanically complex systems, giving a good qualitative and often fairly quantitative agreement with experimental data ( for more recent applications to the study of Rydberg atom collisions cf., e.g., [1][2][3]). Structureless ions of charge Q between 1 and 8 collide with Rydberg target atoms with nuclear charge q=1 and principal quantum number n = 25.…”

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confidence: 99%

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Classical trajectory Monte Carlo calculations of electron capture and ionization in collisions of multiply charged ions with elliptical Rydberg atoms

Lu¹,

Roller-Lutz²,

Lutz³

2000

Phys. Rev. A

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We have performed classical trajectory Monte Carlo studies of electron capture and ionization in multiply charged (Qр8) ion-Rydberg-atom collisions at intermediate impact velocities. Impact parallel to the minor and to the major axis, respectively, of the initial Kepler electron ellipse has been investigated. The important role of the initial electron momentum distribution found for singly charged ion impact is strongly diminished for higher projectile charge, while the initial spatial distribution remains important for all values of Q studied. PACS number͑s͒: 34.60.ϩz, 34.70.ϩe The use of coherent elliptical Rydberg states in ion-atom collision studies ͑for recent papers on the subject cf. ͓1-3͔ and references therein͒ has not only aided the intuitive understanding of the interaction dynamics, it also illuminates the roles of the momentum and the spatial distributions of the target electron states. In classical terms, the momentum distribution can be widely varied simply by changing the eccentricity of the Rydberg ellipse without affecting the energy of the state. In particular, for impact perpendicular to the major axis of the ellipse, the capture cross section displays a maximum if v p ͑the perihelion electron velocity͒ is parallel and equal to the projectile velocity v; this is believed to be due to the matching electron momenta in the initial target and the final projectile state. In contrast, the role of the spatial distribution becomes most clearly visible if the impact velocity vector is adjusted perpendicular to the minor axis of the Rydberg ellipse; in this case, the electrons can be located either between the approaching ion and the target nucleus ͑''upstream geometry''͒ or behind the target nucleus, as seen from the projectile ͑''downstream geometry''͒ without otherwise changing the momentum distribution of the Rydberg state ͑i.e., its angular momentum l and the principal quantum number n). The capture cross section in both cases turns out to be quite different: it is much larger in the upstream case as compared to the downstream case; apparently, in the corresponding region of parameter space the spatial characteristics of the initial state determine the outcome of the collision. These investigations have so far been restricted to collisions with singly charged ions. Recently, however, it has become possible to employ such targets in studies involving multiply charged ions ͓1,4͔. In another context ͑electron capture by multiply charged ions in the presence of an external magnetic field͒ we have found indications ͓5͔ that for increasing projectile charge Q the distortion of the initial state increasingly dominates the influence of different target electron distributions. We have therefore performed an exploratory study of such systems in which a spatially oriented Rydberg atom collides with a multiply charged ion. This is the topic of this paper.We employ the classical trajectory Monte Carlo ͑CTMC͒ method, which is quite useful in particular for the description of quantum-mechanically complex syste...

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confidence: 56%

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confidence: 99%

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confidence: 99%

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confidence: 99%

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Classical trajectory Monte Carlo calculations of electron capture and ionization in collisions of multiply charged ions with elliptical Rydberg atoms

Lu¹,

Roller-Lutz²,

Lutz³

2000

Phys. Rev. A

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“…Finally, we show that for special superpositions of the eigenstates of the bare Hamiltonian (that is, elliptic states [29,67,68]) and in the limit of large principal quantum numbers, the quantum expectation values also have the appropriate quasiclassical ini-tial conditions. Most importantly, elliptic states are not merely theoretical constructs: they have been prepared in the laboratory and some of their properties have already been studied experimentally [8,[69][70][71].…”

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confidence: 99%

Quantum-classical correspondence in the hydrogen atom in weak external fields

et al. 1998

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The complex processes leading to the collisional population of ultra-long-lived Rydberg states with very high angular momentum can be explained surprisingly well using classical mechanics. In this paper, we explain the reason behind this striking agreement between classical theory and experiment by showing that the classical and quantum dynamics of Rydberg electrons in weak, slowly varying external fields agree beyond the mandates of Ehrenfest's theorem. In particular, we show that the expectation values of angular momentum and Runge-Lenz vectors in hydrogenic eigenstates obey exactly the same perturbative equations of motion as the time averages of the corresponding classical variables. By time averaging the quantum dynamics over a Kepler period, we extend this special quantum-classical equivalence to Rydberg wave packets relatively well localized in energy. Finally, the perturbative equations hold well also for external fields beyond the Inglis-Teller limit, and in the case of elliptic states, which yield the appropriate quasiclassical initial conditions, the matching with classical mechanics is complete.

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Electrostatic cage “Stark barrel” for rapidly switching a uniform electric field through arbitrary angles

Horn

Homan

Hwang

et al. 1998

Review of Scientific Instruments

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A cylindrical arrangement of electrodes, together with control electronics, is described that provides uniform electric fields over cm3 volumes in a vacuum, whose angle and magnitude can be switched on a μs time scale. Full 360° field rotation is achieved, and the device allows access for particle or light beams from all sides. Both numerical and analytic descriptions of the general fields are given. Extension to full three-dimensional field control and other variations are described. The device, which was originally designed for crossed-beam collision experiments with keV energy ions and laser-excited Rydberg atoms in field-directed Stark states or coherent-elliptic states, may be more generally useful in atom trapping and cold collisions or in materials and surface science.

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Electron capture from coherent elliptic Rydberg states

Cited by 10 publications

References 35 publications

Classical trajectory Monte Carlo calculations of electron capture and ionization in collisions of multiply charged ions with elliptical Rydberg atoms

Classical trajectory Monte Carlo calculations of electron capture and ionization in collisions of multiply charged ions with elliptical Rydberg atoms

Quantum-classical correspondence in the hydrogen atom in weak external fields

Electrostatic cage “Stark barrel” for rapidly switching a uniform electric field through arbitrary angles

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