Stark-Perturbed<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow><mml:mi mathvariant="normal">L</mml:mi></mml:mrow><mml:mrow><mml:mi>α</mml:mi></mml:mrow></mml:msub></mml:mrow></mml:math>Decay in Flight

Sellin, I. A.; Moak, C. D.; Griffin, P. M.; Biggerstaff, J.A.

doi:10.1103/physrev.188.217

Cited by 23 publications

(6 citation statements)

References 7 publications

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“…In conclusion, it seems that the multiphoton ionization probability for xenon atoms with a Ndglass laser pulse is g (k) times as large as that obtained when the excitation source is an ideal Since the observation by Bashkin and co-workers 1,2 and by Sellin et al 3 of electric-field-induced modulations in the time decay of beamfoil-excited hydrogen atoms, the study of modulated decays has proved to be of considerable importance in the field of beam-foil spectroscopy. In particular, the discovery of zero-field quantum beats by Andrst, 4 indicating that foil-excited atoms are frequently aligned, prepared the way for the introduction of a large number of high-single-mode laser pulse.…”

mentioning

confidence: 76%

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Measurement ofS−PCoherence in the Beam-Foil—Excitedn=2State of Atomic Hydrogen

1974

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confidence: 76%

“…Recent experiments have demonstrated that electrons ejected from ferromagnetic tips by field emission are polarized. 3 Our spectrometer was a superheterodyne type operating in the K u band. The pressure-sealed TE 102 -mode rectangular cavity had special microwave chokes which prevented leakage of microwave radiation.…”

Section: Measurement Of S-pmentioning

confidence: 99%

Measurement ofS−PCoherence in the Beam-Foil—Excitedn=2State of Atomic Hydrogen

1974

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“…Eine andere Sonderstellung des Wasserstoffs in der Ionenstrahlspektroskopie besteht darin, dab er ein bevorzugtes Studienobjekt ftir ,,Quantum beats" [3] ist, nicht nut der Stark-induzierten [4,5], sondern auch der Nullfeldbeats [6,7]. Mit Hilfe der letzteren liiBt sich das ,,Alignment" folienangeregter Wasserstoffatome messen, das zum Verst/indnis des Ionen-Folien-Wechselwirkungsmechanismus von Bedeutung ist, wobei sich auch hier eine Besonderheit des Wasserstoffs gegeniiber anderen Atomen oder Ionen andeutet (negatives Alignment [7]).…”

Section: A Einleitungunclassified

“…In solchen F~illen k6nnte man sich den Effekt zunutze machen, dab bei Verwendung yon Molekiilionen als Prim/irteilchen keine Quantum beats auftreten, weil die Dissoziationspartner des Molektils dicht hinter der Folie r~iumlich noch so benachbart sind, daB sie sich gegenseitig beeinflussen [4,8]. In solchen F~illen k6nnte man sich den Effekt zunutze machen, dab bei Verwendung yon Molekiilionen als Prim/irteilchen keine Quantum beats auftreten, weil die Dissoziationspartner des Molektils dicht hinter der Folie r~iumlich noch so benachbart sind, daB sie sich gegenseitig beeinflussen [4,8].…”

Section: A Einleitungunclassified

Ionenstrahlspektroskopie mit Wasserstoffionen als Primärteilchen

et al. 1973

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Relative initial populations of foil-excited hydrogen atoms in the 2p, 3s, 3p, and 3d states are determined by measuring the Balmer-0~ and Lyman-e emissions simultaneously. The data are analyzed by a computer program which takes into account the correlation of both emissions. The results show a dependence on the kind of incident ions: molecular ions give more light and lead to more pronounced excitation of higher angular momentum states than do atomic ions. A possible mechanism to explain this "molecule effect" is discussed qualitatively. A. EinleitungDas Wasserstoffatom nimmt in der Ionenstrahlspektroskopie [1] in verschiedener Hinsicht eine Sonderstellung ein. Da es ein Einelektronensystem ist, k6nnen seine angeregten Zusfiinde und deren mitflere Lebensdauern und Ubergangswahrscheinlichkeiten [2] exakt berechnet werden. Wasserstoff sollte also eine besonders geeignete Testsubstanz ft'lr die Ionenstrahlspektroskopie sein. Auch im Hinblick auf die noch weitgehend ungekl~irte Frage der Ionen-Folien-Wechselwirkung sollte man bei Wasserstoff die besten Aussichten auf einen Erfolg der theoretischen Behandlung erwarten.Diesen Vorteilen stehen experimentelle Nachteile gegentiber. Manche Lebensdauern im Wasserstoff-Termschema, insbesondere die der s-Zust/inde, sind fiir die Messung unbequem grog. Die/-Entartung der Niveaus im reinen (1/r2)-Coulombfeld ftigt einerseits zu dem in der Ionenstrahlspektroskopie sowieso vorhandenen Kaskadenproblem die Komplikation hinzu, daB Uberg/inge mit verschiedenen Lebensdauern sich optisch nicht trennen lassen und verursacht andererseits eine groBe Empfindlichkeit der Niveaus gegeniiber elektrischen Feldern (Starkeffekt): Schon wenige V/cm bewirken z.B. bei den Niveaus der H~-Linie eine megbare Ver/inderung der mittleren Lebensdauern. Will man dies 9*

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“…The cross sections ~a(to) , Pa(~o) for the capture of an electron by a positive point charge into n = 2 states are discussed for instance by Hughes et al [15], Garcia [16], Alguard and Drake [17], for various energies up to 340 keV. In the range from 150 keV to 340 keV some measured sa(%), vet(to) cross sections for H + on C-targets are available from [17][18][19]. Garcia [163 points out that at high energies the s states are populated in excess of the p states.…”

Section: Pao(to)-val(to)mentioning

confidence: 97%

Influence of surface electric fields on the alignment of the hydrogen-2p state after beam-foil-excitation

Kupfer

Winter

1978

Z Physik A

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In contrast to other atomic systems, foil excited hydrogen or hydrogen-like atoms show a negative alignment for various energy ranges. We suggest that this particular behaviour results from the degeneracy of different L states in hydrogenic systems and an observable influence of a surface electric field modifying the initial alignment via Stark effect. L IntroductionThe beam-foil interaction process produces a difference in the magnetic sublevel populations of the excited states. This population asymmetry can be observed by the radiation emitted in transitions from excited states. If a foil is oriented perpendicular to the beam axis, axial and reflection symmetry with respect to this axis hold and only linear polarization is measured. From these measurements one determines the alignment (Po-o -P~a)/(Vao + Pal) of an excited p state, where the density matrix element %M,~ is proportional to the cross section for the formation of a state [nLML).As a particular result the alignment of the beam-foil excited states of hydrogen [1][2][3] and of hydrogen-like ions [4] is negative over a wide energy range in contrast to non-hydrogenic systems, for which always positive alignment [5] is found. We use the assumption of Eck [6] and Lombardi [7] that a strong electric field exists at the surface of a carbon foil in order to explain the particular behaviour ofhydrogenic systems. Their energy levels are strongly affected by an electric field, which may cause the alignment to change sign as will be shown below. II. Theoretical ModelIn the present work we discuss the alignment of a hydrogen-2p state as determined from the polarization * This work is part of the research program of the "Sonderforschungsbereich 161" supported by the Deutsche Forschungsgemeinschaft of the Lyman-e radiation emitted perpendicular to the beam. We refer to the following geometry: the beam and the detector axis coincide with the z and y direction, respectively. The foil is located in the x-y-plane. An ensemble of excited ions or atoms leaves the foil at a time t o. Postulating, as is usually done, that the excitation process results from pure electrostatic interactions, the initial density matrix of the excited states factorizes into an isotropic spin and an anisotropic angular momentum matrix (nLML[a(to) In' I2M~).(The angular momentum basis is characterized by n, the principal quantum number, L, the angular momentum, and ML, the corresponding magnetic quantum number with respect to the z direction as quantization axis). We recall that the hermiticity of a(to)From symmetry of reflection at the x-z-plane follows (lb) and axial symmetry about the beam direction means (lc)The angular momentum density matrix of the foilexcited hydrogen n=2 state at time t= t o is given by 0340-2193/78/0285/0003/$01.00

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Stark-PerturbedLαDecay in Flight

Cited by 23 publications

References 7 publications

Measurement ofS−PCoherence in the Beam-Foil—Excitedn=2State of Atomic Hydrogen

Measurement ofS−PCoherence in the Beam-Foil—Excitedn=2State of Atomic Hydrogen

Ionenstrahlspektroskopie mit Wasserstoffionen als Primärteilchen

Influence of surface electric fields on the alignment of the hydrogen-2p state after beam-foil-excitation

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