Orientation and alignment in charge exchange processes involving sodium atoms studied by semi-classical molecular theory

Courbin, C; Machholm, Mette; Lewartowski, E

doi:10.1007/bf01426074

Cited by 7 publications

(5 citation statements)

References 19 publications

(30 reference statements)

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“…In their experimental study of charge transfer from an initially oriented Na * (3p −1 ) state, Richter et al [2] observe left-right asymmetries (or Φ = 0/Φ = π asymmetries) in the Na * (3p −1 ) → H * (n = 2) DCS. These asymmetries, due to the asymmetry of the 3p −1 initial state, are also predicted theoretically by Dubois et al [6] and Courbin et al [16] using semiclassical methods. Here we examine the CTMC deflection angle for each trajectory as a function of the impact parameter and define the DCS for each channel considered (see Sect.…”

Section: Proton Velocity Perpendicular To the Oz Axissupporting

confidence: 78%

“…The preferred p −1 orientation in the final state can be explained by invoking the inverse collision Na + + H * (2p): the dominance of the p −1 → p −1 probability allows us to assert that the velocity matching argument applies to this quasi-resonant reaction in the velocity range presently studied. However, although it seems to allow a very simple interpretation of charge transfer mechanism involving oriented states, this criterion is not valid at lower collision velocity, as Courbin et al [16] have shown in the non-resonant Li + −Na * (3p) case.…”

Section: Proton Velocity Perpendicular To the Oz Axismentioning

confidence: 99%

“…Orientation effects in the initial state have been analysed using the charge exchange probabilities but no connection could be made to experimental results. Some semiclassical calculations, using either an AO [6] or MO basis [16,17] have been performed where the orientation is analysed not only in the initial state but also in the final p state. The comparison of CTMC state-to-state probabilities to quasi-exact ones provides a stringent test of the validity of this method.…”

Section: Oriented-to-oriented State Charge Transfermentioning

confidence: 99%

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Classical trajectory study of orientation and alignment effects for charge exchange processes in H+- Na*(3p m) collisions

Fourré¹,

Courbin²

1996

Z Phys D - Atoms, Molecules and Clusters

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The orientation and alignment effects for charge exchange in H + + Na * (3p) collisions are studied using the classical trajectory Monte-Carlo method in the energy range from 1 to 8 keV. For Na * (3p −1 ) → H * (2s, 2p ±1 ) transitions a large orientation effect is predicted by the probability functions, in very good agreement with semiclassical calculations. Angular differential cross sections are also calculated and interpreted using the impact parameter dependence of the proton deflection angle. They predict left-right asymmetry in agreement with semiclassical calculations or experimental results, but slightly smaller. Another geometry, not experimentally realized, is considered, where the proton velocity is parallel to the quantization axis of the p ±1 oriented states. Charge exchange from different aligned states with respect to the direction of the projectile velocity is also investigated, but the alignment effects are not as well described as the orientation effects. Total cross sections from oriented or aligned states with cylindrical symmetry around the projectile velocity direction are calculated and allow the hypothesis of velocity matching to be tested.

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Section: Proton Velocity Perpendicular To the Oz Axissupporting

confidence: 78%

Section: Proton Velocity Perpendicular To the Oz Axismentioning

confidence: 99%

Section: Oriented-to-oriented State Charge Transfermentioning

confidence: 99%

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Classical trajectory study of orientation and alignment effects for charge exchange processes in H+- Na*(3p m) collisions

Fourré¹,

Courbin²

1996

Z Phys D - Atoms, Molecules and Clusters

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“…In all cases, the motion of the valence electron is calculated assuming single particle motion around a frozen core. In the first calculation, the model Klapisch potential is employed for this purpose [7,8]:…”

mentioning

confidence: 99%

Orientational Dichroism in the Electron-Impact Ionization of Laser-Oriented Atomic Sodium

et al. 1998

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We report the first experimental observation of "orientational dichroism" in electron impact-induced ionization. ͑e, 2e͒ experiments have been performed on pure angular momentum states 3P 3͞2 , m F 13 and m F 23 of the sodium atom, excited by right-and left-handed circularly polarized laser light. Our results show that the angular correlation of the final-state electron pair is strongly dependent on the m L sublevel populated. Comparison with calculation demonstrates the dependence of the dichroism on details of the scattering dynamics. [S0031-9007(97)04999-5] PACS numbers: 34.80.Dp A detailed knowledge of the ionization process is essential to our understanding of, and progress in, such diverse fields as discharge and plasma physics, fusion physics, laser physics, and the physics and chemistry of the upper atmosphere. The most accurate information on this process is derived from kinematically complete ͑e, 2e͒ experiments, in which the energies and momenta of all reaction participants and products are determined [1]. We report here on an ͑e, 2e͒ experiment in which the projection quantum number for an excited atomic target in a pure nonzero angular momentum state is also resolved. Using laser pumping techniques, an atomic sodium target is laser excited to the 3 2 P 3͞2 F 3, m F 13 or m F 23 hyperfine states. These states consist of maximal projections of the nuclear spin (I 63͞2), the orbital angular momentum (m L 61), and the electron spin (S 61͞2) along the laser beam direction.If neither the projection quantum numbers of the incident electron nor the target are resolved, the (e, 2e) differential cross section is simply a scalar invariant with respect to a joint rotation of the incoming and outgoing electron momenta p 0 , p a , and p b , respectively. This basic symmetry is destroyed by an initial orientation and/or alignment of the target. The (e, 2e) cross section is then irreducibly described by a set of tensorial parameters whose number is determined by the symmetry of the initially prepared target state [2]. Generally, the cross section for the ionization of a target with total angular momentum J can be written as [2]where L ͑i͒ 0 are tensorial components along the quantization axis of the target describing the dynamics of the ionization process and r i0 are the state multipoles describing the M-state population of the target. The transformation properties of L ͑i͒ 0 are determined by the rank i of the associated tensor. The solid angles of the momenta p a , p b with respect to p 0 are labeled by dV a , dV b , respectively.In the present case of the Na 3P 3͞2 state, neglecting spin-orbit interactions and for unpolarized primary electrons it suffices to consider Eq. (1) with respect to the orbital angular momentum L 1 for singlet and triplet scattering. Then the cross section is described only by three tensorial components L ͑i͒ 0 , which can be written in terms of the ionization cross sections for the individual magnetic substates s L,m L :L ͑2͒ 0 1 p 6 ͑s 1,1 2 2s 1,0 1 s 1,21 ͒ .The scalar component L ͑0...

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“…For singly and doubly charged projectiles also semiclassical closecoupling methods succesfully predicted experimental results (e.g. Gieler et al 1993a, Dubois et al 1993, Courbin et al 1994, Rod and Nielsen 1995. With highly charged ions at present the use of this method is prohibited due to practical limits imposed on the basis set size.…”

Section: Introductionmentioning

confidence: 61%

Anisotropy and polarization in charge changing collisions of with Na(3s) and laser aligned Na(3p)

Schippers¹,

Hoekstra²,

Morgenstern³

et al. 1996

J. Phys. B: At. Mol. Opt. Phys.

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Absolute cross sections for C 3+ (6→5) emission at 465.7 nm after collisions of C 4+ ions with ground state Na(3s) and laser excited aligned Na(3p) atoms are measured over the collision energy range of 3-7 keV amu −1 . For Na(3s) polarizations are observed by measuring the linear polarization of the emitted light. In these collisions the polarization is found to be 0.33 and almost independent of the collision energy. Cross sections for collisions with the Na(3p) target are up to five times larger than for collisions with Na(3s). Slightly larger cross sections are measured when the laser excited Na(3p) target is -aligned as compared to a -alignment. Classical trajectory Monte Carlo (CTMC) calculations agree excellently with the experimental findings and yield predictions of strong positive polarizations for electron capture also from aligned Na(3p), indicating preferential capture to m = 0 states,.

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Orientation and alignment in charge exchange processes involving sodium atoms studied by semi-classical molecular theory

Cited by 7 publications

References 19 publications

Classical trajectory study of orientation and alignment effects for charge exchange processes in H+- Na*(3p m) collisions

Classical trajectory study of orientation and alignment effects for charge exchange processes in H+- Na*(3p m) collisions

Orientational Dichroism in the Electron-Impact Ionization of Laser-Oriented Atomic Sodium

Anisotropy and polarization in charge changing collisions of with Na(3s) and laser aligned Na(3p)

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