Resonant coherent excitation of channeled ions

Moak, C. D.; Datz, S.; Crawford, Oakley H.; Krause, H. F.; Dittner, P.F.; Campo, J. Gómez del; Biggerstaff, J.A.; Miller, P.D.; Hvelplund, P.; Knudsen, H.

doi:10.1103/physreva.19.977

Cited by 85 publications

(17 citation statements)

References 23 publications

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“…We changed the tilt angle, h, also in the 0 0 4 and 1 " 1 1 planes. Resonances corresponding to kY l (1,1), (1,2), (1,3), (1,4) for the 0 0 4 plane, and to kY l 1Y 1, (1,3) for the 1 " 1 1 plane were observed.…”

Section: Resultsmentioning

confidence: 95%

“…Since then, much progress in the understanding of RCE has been made in the last two decades [3]. The removal of the degeneracy of 2s and 2p states induced by the crystal and wake ®elds were investigated in detail experimentally and theoretically [2,4,5]. Measurements of the charge fraction of emerged ions and X-ray have been recently reported [6,7].…”

Section: Nuclear Instruments and Methods In Physics Research B 135 (1mentioning

confidence: 99%

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Resonant coherent excitation of relativistic Ar17+ ions channeled in a Si crystal

Azuma

Ito

Yamazaki

et al. 1998

Nuclear Instruments and Methods in Physics Research Section B:

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We observed resonant coherent excitation (RCE) of 1s electron to n 2 states in Ar 17 through measurements of the survived fraction of 390 MeV/u hydrogen-like Ar 17 channeled in a Si crystal. We adopted a totally depleted Si surface barrier detector as a target crystal as well as a probe of the energy deposition. The charge state of emerged ions was measured by a combination of a charge separation magnet and a 2D-position sensitive detector. We observed the RCE for planar channeled ions by tilting the target Si crystal from the direction of 1 1 0 axis in the 2 " 2 0, 0 0 4, and 1 " 1 1 planes. Prominent resonances at tilt angles under the resonance condition were observed. Moreover, each resonance pro®le is split into several lines due to the l Á s interaction and the Stark eect originating in the static crystal ®eld. The energy deposition in the crystal gives the information of the amplitude of the ion trajectory. The resonance peak position, intensity and width in the survived fraction of Ar 17 re¯ect the position dependent strength of the crystal ®eld, the RCE and the electron loss probabilities. They are in good accord with our calculation of the transition energy and probability. Ó 1998 Elsevier Science B.V.

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Section: Resultsmentioning

confidence: 95%

Section: Nuclear Instruments and Methods In Physics Research B 135 (1mentioning

confidence: 99%

Resonant coherent excitation of relativistic Ar17+ ions channeled in a Si crystal

Azuma

Ito

Yamazaki

et al. 1998

Nuclear Instruments and Methods in Physics Research Section B:

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“…When one of these frequencies coincides with v r =AF;///z, where AEjj is the energy difference between electronic states i and j of the ion, for example, the n = 1 -• 2 transition frequency of a one-electron ion, a fraction of the incident ground-state ions can become excited provided that electric dipole selection rules are satisfied. This phenomenon, called resonant coherent excitation (RCE), has been demonstrated and extensively studied for swift, low-Z (4 < Z < 12) one-and two-electron ions moving in facecentered-cubic (fee) lattices such as Ag and Au [1][2][3][4][5][6][7]. Previous studies have shown that excitation occurs in every harmonic K. Here, we report the first observation of RCE in a non-fee lattice and we show that the alternating atomic spacing along an atomic row can selectively eliminate or enhance excitation in certain harmonics.…”

Section: Interferences In Resonant Excitation Of Hydrogenic Channeledmentioning

confidence: 99%

Interferences in resonant excitation of hydrogenic channeled ions

Datz

et al. 1993

Phys. Rev. Lett.

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We have observed selection rules for the resonant excitation of swift hydrogenlike ions (Z =6,7) axially channeled in the Oil) direction of a diamond lattice (silicon). The resonant excitation arises from a coherent periodic perturbation by the atoms in the bounding crystal rows. We show that the selection rules are the consequence of destructive and constructive interference in the quantum mechanical transition amplitude for excitation.

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“…Early experiments with He 1 ions after the passage through thin crystal foils were not conclusive [2][3][4], since loosely bound electrons will not survive within the bulk of a metal. First evidence for RCE in a crystal was reported by Datz and co-workers [5][6][7] by observation of charge fractions of tightly bound hydrogenlike and heliumlike ions with MeV energies after the passage through thin crystals of Au and Ag. The enhanced ionization probabilities for electronically excited ions lead, under resonance conditions, to modified charge fractions which provide an unequivocal signature of RCE in a solid.…”

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confidence: 96%

Resonant Coherent Excitation of Fast Hydrogen Atoms in Front of a LiF(001) Surface

et al. 1997

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We have scattered protons and hydrogen atoms with energies of some keV from a LiF(001) surface under a grazing angle of incidence. From the intensity of Lyman-a radiation (transition from n 2 to n 1, l 121.6 nm) as a function of projectile energy for different azimuthal orientations of the crystal surface, we find clear evidence for a resonant coherent excitation of n 2 states of hydrogen atoms in the oscillating electric field in front of the insulator surface. [S0031-9007(97)04713-3] PACS numbers: 79.20. Rf, 34.50.Fa, 34.70. + e When fast atoms or ions interact with a crystal under channeling conditions the target atoms induce oscillating electric fields in the projectile frame. Okorokov [1] predicted that for a corresponding setting of the projectile velocity and the crystal orientation these fields will stimulate a resonant coherent excitation (RCE) of electronic states in the projectiles. Early experiments with He 1 ions after the passage through thin crystal foils were not conclusive [2-4], since loosely bound electrons will not survive within the bulk of a metal. First evidence for RCE in a crystal was reported by Datz and co-workers [5-7] by observation of charge fractions of tightly bound hydrogenlike and heliumlike ions with MeV energies after the passage through thin crystals of Au and Ag. The enhanced ionization probabilities for electronically excited ions lead, under resonance conditions, to modified charge fractions which provide an unequivocal signature of RCE in a solid. Kupfer et al. [8] proposed to make use of the electric fields that extend to the vacuum region in front of a solid and to excite electronic transitions in projectiles scattered in front of the surface ("surface channeling"). Attempts to observe RCE via optical transitions in He 1 ions failed [9]; however, recently Kimura et al.[10] found evidence for RCE by observing changes in the B 41 ͞B 51 charge ratios for MeV boron ions scattered under grazing incidence from a SnTe(100) surface. A structure in those ratios at a projectile energy of about 5.85 MeV is attributed to the n 1 to n 2 excitation of hydrogenlike boron ions ͑B 41 ͒ via the second harmonic of the oscillating electric fields in front of the surface.In this Letter we report on the first observation of RCE obtained for the scattering of fast atomic projectiles from the surface of an ionic crystal, here LiF(001). Our experiments demonstrate that making use of insulator instead of metal surfaces results in new attractive features which make ionic crystals well suited for detailed studies on resonant coherent excitation phenomena induced in the interaction of atomic projectiles with a solid target. We present results on the excitation of n 2 in atomic hydrogen studied by the subsequent decay via Lyman-a radiation ͑l 121.6 nm͒. This work can be considered as the first successful resonant excitation of atomic levels with loosely bound electrons (binding energy some eV) in the interaction of fast atoms with solid matter.Making use of an ionic crystal surface instead of metal ...

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Resonant coherent excitation of channeled ions

Cited by 85 publications

References 23 publications

Resonant coherent excitation of relativistic Ar17+ ions channeled in a Si crystal

Resonant coherent excitation of relativistic Ar17+ ions channeled in a Si crystal

Interferences in resonant excitation of hydrogenic channeled ions

Resonant Coherent Excitation of Fast Hydrogen Atoms in Front of a LiF(001) Surface

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