Left-right asymmetry in superelastic collisions of polarized electrons with unpolarized laser-excited sodium atoms

Nickich, V; Hegemann, Tim; Bartsch, Manfred; Hanne, G F

doi:10.1007/bf01437529

Cited by 28 publications

(11 citation statements)

References 16 publications

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“…Recently, Jiang et al [14] determined the cross section for inelastic scattering of 2 eV electrons inducing 3 P -4 S transition in sodium. In several laboratories superelastic collisions of electrons with Na(3P) atoms were also studied [11,12,[15][16][17][18][19]. A comprehensive review of these topics may be found in paper by Andersen et al [20].…”

Section: Introductionmentioning

confidence: 98%

Method of investigation of electron impact induced transitions between excited atomic levels

Stacewicz

1993

Z Phys D - Atoms, Molecules and Clusters

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Abstract.A method for the measurement of rate constants for inelastic collisions between thermal electrons and excited atoms is presented. The measurements were performed in a mixture of saturated caesium and sodium vapor. Electrons were generated by ionization of caesium vapour by intense resonant dye laser pulses. Pulses of second dye laser, delayed with respect to the first one, excited the sodium atoms to the 3P level. Subsequently Na(3P) atoms were excited to higher levels by collisions with electrons. The fluorescence intensity from these levels served as a measure of the rate constant for these transitions. The method was used to investigate the electron impact induced 3P-4P excitation.

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Section: Introductionmentioning

confidence: 98%

Method of investigation of electron impact induced transitions between excited atomic levels

Stacewicz

1993

Z Phys D - Atoms, Molecules and Clusters

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“…3p electron-impact excitation in sodium. Subsequently, the technique was widely applied [8][9][10][11].Interestingly, the observed pattern for the angular momentum transfer as a function of the scattering angle showed a characteristic behavior, essentially independent of the collision energy and even the actual target. For electron-impact induced S !…”

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confidence: 99%

“…3p electron-impact excitation in sodium. Subsequently, the technique was widely applied [8][9][10][11].…”

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confidence: 99%

Propensity Rules for Angular Momentum Transfer in Electron-Impact Excitation and Deexcitation

1999

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Following the recent investigation of Shurgalin et al. [Phys. Rev. Lett. 81, 4604 (1998)], electronimpact induced 3s ! 3p and 4s ! 3p transitions in atomic sodium are studied theoretically. A propensity rule for the angular momentum transfer is supported for scattering angles below 60 ± and incident energies below 20 eV. Excellent agreement between the predictions from an R matrix with pseudostates calculation and the experimental data is obtained and provides credibility to the present study.PACS numbers: 34.80.Dp Ever since the pioneering discussion by Kohmoto and Fano [1], a parameter of particular interest in the detailed study of atomic collisions has been the so-called "orientation" of the target, which describes the sense of circulation of the active electron(s) around the atomic core. This parameter can be studied in scattered-particlepolarized-photon coincidence experiments, in which the circular polarization P 3 of the light emitted perpendicular to the scattering plane is determined [2]. For the simplest case of 1 S ! 1 P o excitation without spin exchange and relativistic effects, P 3 , the orientation O 12 and the angular momentum transfer L Ќ are related through P 3 22O 12 2L Ќ . For more complicated situations, the result becomes P 3 2fL Ќ [2]. The factor f describes depolarization effects due to atomic fine structure and hyperfine structure, cascading if more than one photon can be emitted, and possibly relativistic effects.Alternatively, the angular momentum transfer can be studied in the "time-reversed" experiment, starting with a laser-prepared state. Following early work by Hertel et al. [3,4], this method was further developed by the NIST group [5-7] who generated benchmark data for 3s ! 3p electron-impact excitation in sodium. Subsequently, the technique was widely applied [8][9][10][11].Interestingly, the observed pattern for the angular momentum transfer as a function of the scattering angle showed a characteristic behavior, essentially independent of the collision energy and even the actual target. For electron-impact induced S ! P o excitation, almost without exception (see Ref.[12] for a rare example), the value of L Ќ is positive for small scattering angles u and increases with u to a maximum beyond which the variation becomes more individual. (See Ref. [13] for an extensive compilation of the available data.) Triggered by these results, considerable effort has been directed into finding a solid theoretical foundation for this empirical propensity rule, the Kohmoto-Fano paper being an early example. Propensity rules for orientation have also been formulated and discussed for heavy-particle impact excitation [14], and efforts have concentrated on exploring the generality of these rules [15,16].For electron-atom collisions, a significant step beyond the Kohmoto-Fano work was the analysis by Madison and Winters [17]. After pointing out a phase problem in the Kohmoto-Fano paper, they discussed the orientation parameter in terms of the charge q of the projectile, with q 61 for positron and...

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“…However, to illustrate explicitly the role of the orientation of 'p' orbital (i.e. M L = +__ 1), one can express SA (1/2) in the natural frame of [7,8].…”

Section: Sa(t/2)= Ill2mentioning

confidence: 99%

“…Further, if the atomic fine-structure levels are resolved, a left-right scattering asymmetry of the polarized electrons is observed [4][5][6][7]. This spin effect (the so called fine structure effect) results from an interplay between the orbital angular momentum orientation of the separated fine structure levels and the exchange interaction [8]. In view of the experiments being in progress at Bielefeld University by Baum and collaborators [9] for the spin-polarized electron-lithium atom scattering, it is desirable to study theoretically the above spin effects in the electron-lithium scattering.…”

Section: Introductionmentioning

confidence: 95%

Spin-resolved orientation, depolarization and left-right asymmetry in electron-lithium scattering

Jain

Purohit

Mathur

1994

Z Phys D - Atoms, Molecules and Clusters

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Abstract.A two-potential tocalised exchange (TPLE) approach is used to study the role of spin dependence in the inelastic scattering of electrons by lithium atoms at intermediate energies. Results are presented for the spin-resolved orientation parameters (L s, L~ r, and L±) in the polarized-electron impact resonant (2 s-2p) excitation of polarized-lithium atom. Results are also obtained for the depolarization (P2/Pe) in the polarized-electron impact resonant (2s-2p) and nonresonant (2s-3p) transition in unpolarized lithium atom. Further in the case when the fine structure splitting of the target is resolved, we also investigate the left-right scattering asymmetry S A (1/2) for the polarized-electron superelasticalty scattered from unpolarized 2pl/2 and 3pl/2 states.

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Left-right asymmetry in superelastic collisions of polarized electrons with unpolarized laser-excited sodium atoms

Cited by 28 publications

References 16 publications

Method of investigation of electron impact induced transitions between excited atomic levels

Method of investigation of electron impact induced transitions between excited atomic levels

Propensity Rules for Angular Momentum Transfer in Electron-Impact Excitation and Deexcitation

Spin-resolved orientation, depolarization and left-right asymmetry in electron-lithium scattering

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