Observation of Coherent Electron-Density-Distribution Oscillations in Collision-Averaged Foil Excitation of the<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>n</mml:mi><mml:mo>=</mml:mo><mml:mn>2</mml:mn><mml:mn /></mml:math>Hydrogen Levels

Sellin, I. A.; Mowat, J. R.; Peterson, R. S.; Griffin, P. M.; Laubert, R.; Haselton, H.H.

doi:10.1103/physrevlett.31.1335

Cited by 62 publications

(18 citation statements)

References 8 publications

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“…We consider the bound state Hilbert space (E <0) of the nonrelativistic Hamilton operator H=2~_P2 Zr (2) (Z: nuclear charge; #: reduced mass). Henceforth, we will neglect electronic and nuclear spins.…”

Section: Su(2) X Su(2) Description Of Hydrogenmentioning

confidence: 99%

“…In addition to the nonstatistical population of different magnetic substates [lm} of a level with angular momentum l known as Zeeman coherence a different type of coherence can be observed in hydrogen. The near degeneracy of/-states within a principal shell allows the coherent population of states with different angular momenta [1][2][3][4]. This type of coherent excitation will be named angular momentum coherence in the following.…”

Section: Introductionmentioning

confidence: 98%

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Group-theoretical classification of angular momentum coherences in hydrogen

Burgdörfer

1983

Z Physik A

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A new classification scheme of angular momentum coherences based on the dynamical symmetry group 0 4 of hydrogen is proposed. The existence of a specific constant of motion, the Runge-Lenz vector, enables an extension of the Fano-Macek approach to mixed-/ coherences observed in inelastic atomic collision processes. Using a SU(2) x SU(2) pseudospin formulation a correspondence between the complete n-shell density matrix and the expectation values of multipoles of the angular momentum and the Runge-Lenz vector is established. Explicit expressions are given for n = 2 and n = 3.

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Section: Su(2) X Su(2) Description Of Hydrogenmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 98%

Group-theoretical classification of angular momentum coherences in hydrogen

Burgdörfer

1983

Z Physik A

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“…Macek's analysis of the negative-going damped sinusoidal difference signal obtained in a later collaborative experiment with Gaupp et al (whose data at overlapping energies corroborated those of Ref. 2), led them to assert that the electron emerges from the foil ahead of the proton with overall displacements ~ 1/2 a 0.…”

mentioning

confidence: 58%

Coherent electron density distribution oscillations in electron capture by fast protons in helium

Liljeby¹,

Mannervik²,

Hultberg³

et al. 1978

Z Physik A

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Assuming the validity of a recent model of Lyman-~ beat behaviour from fast H atoms under conditions of reversal of an applied electric field, we find strong electric dipole density distribution oscillations in electron capture to n=2 levels of hydrogen by fast protons (~ 2 au) in helium. Possibilities for testing relative orbital phase calculations in charge-transfer theory, and for making comparisons between beam-surface and single ion-atom collision models of projectile passage through solids exist.Using a quantum-beat technique originated by Eck I' collision-averaged production of oscillating electric dipole moments was first established by S 2 ellin et al. in an experiment concerning C foil excitation of the hydrogen n=2 states (~ = a~2s+ + b 42 ). Earlier, Burns and Hancock 3 had seen quantu~ beat frequencies characteristic of s-d beats in H~ emission subsequent to foil excitation, and interpreted them in terms of coherent excitation of these states, suggesting the existence of oscillating excited state quadrupole moments as a source of such beats. The electric dipole moment oscillations inherent in the data of Ref. 2 normally do not manifest themselves in quantum beats, since a con~non final state must, in E] approximation, have the same parity as one of the states in an opposite parity mixture. Thus the interference term in the square of the E] radiation matrix element vanishes. An applied electric field along the beam axis (z) renders the cross term observable by opening a decay channel for the perturbed s state to the ground state, but also produces ordinary Stark beating of s and p states which occurs in the absence of any excitation coherence whatever. Realizing that the field-induced beats depend on I~] but not on its direction, Eck suggested that complete isolation of the excitation coherence could be achieved by simply subtracting the beat pattern for antiparallel field from that for parallel field. Macek's analysis of the negative-going damped sinusoidal difference signal obtained in a later collaborative experiment with Gaupp et al. (whose data at overlapping energies corroborated those of Ref. 2), led them to assert that the electron emerges from the foil ahead of the proton with overall displacements ~ 1/2 a 0.It is of interest from several points of view to inquire whether such dipole moments are characteristic of some intrinsically solid-state surface effect (including beam-induced exit-surface electric fields), or whether they are characteristic of a variety of single ion-atom collision processes, like electron capture to excited states. The relative phases of charge transfer amplitudes to opposite-parity excited states could prove to be a more sensitive test of rival electron capture theories, which are often noted to produce reasonably good agreement concerning total excited capture cross-sections, but are known to differ appreciably in details like differential angular distributions. Disentangling intrinsic solidstate effects from final surface capture events by comparing gas wi...

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“…By considering the collision symmetry of the normal foil excitation geometry, where the quantization axis is chosen in the direction of the beam velocity, the corresponding excitation density matrix a at t =0 does not depend on the sign of mz. In the absence of nuclear spin, the matrix is given by (2) with a(II'lmil)= <l f (Imt)llf (I' ml)! exp(i05(ll'lmll))>, (3) where the angular brackets refer to collision averages and 05 (II' lmll) = 05 (l' lmil)--05 (I lmzl).…”

Section: Theoreticalmentioning

confidence: 99%

“…Soon after the Eck's proposal, two groups carried out the measurement on electric field induced modulations in the time decay of foil-excited hydrogen atom [2,3]. They have clearly showed the role of the external electric field.…”

Section: Introductionmentioning

confidence: 98%

Stark beats of Lyman-α emission of foil-excited hydrogen atom

Ishii

Nakajima

Masui

et al. 1992

Z Phys D - Atoms, Molecules and Clusters

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Abstract. The Stark beats of Lyman-e emission due to n = i -2 transition of hydrogen atom have been studied by the beam-foil method. After passage through a thin carbon foil, the static electric field of 500 V/cm was applied to the beam in the direction either parallel to or anti-parallel to the the beam velocity. The linearly polarized emission was measured by using a toroidal mirror at a Brewster's angle reflection. When the direction of the applied electric field is reversed, an appreciable phase shift was observed. The analysis of the data leads to the complete determination of the density matrix of the H(n = 2) atoms at the time of their production.

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Observation of Coherent Electron-Density-Distribution Oscillations in Collision-Averaged Foil Excitation of then=2Hydrogen Levels

Cited by 62 publications

References 8 publications

Group-theoretical classification of angular momentum coherences in hydrogen

Group-theoretical classification of angular momentum coherences in hydrogen

Coherent electron density distribution oscillations in electron capture by fast protons in helium

Stark beats of Lyman-α emission of foil-excited hydrogen atom

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