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  • 1
    Electronic Resource
    Electronic Resource
    2π spectrometer: A new apparatus for the investigation of ion surface interaction (1996)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 67 (1996), S. 2163-2170 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A new spectrometer for studying ion surface interaction is described. This apparatus is built around a secondary electron and ion detector with a very large acceptance angle and made of 16 individual microchannel plate detectors located on a half sphere. A simultaneous detection of the scattered projectiles with an additional position sensitive detector allows measurements of the correlation between all these particles using a multicoincidence technique. With this spectrometer, a large variety of measurements are possible such as the energy spectra of the secondary electrons as well as the statistics of the number of ejected electrons, the scattering pattern of the reflected projectiles and their charge-state distribution, the analysis of the sputtered ions. Some examples are given concerning the impact of multiply charged ions on a LiF single crystal. The dependence of the secondary electron multiplicity as a function of the charge state, of the surface channeling condition, and of the scattering angle of the reflected ion, is given as a type of information provided by the analysis of the correlation. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1147031
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  • 2
    Electronic Resource
    Electronic Resource
    Berry phase and supersymmetric topological index (1995)
    College Park, Md. : American Institute of Physics (AIP)
    Journal of Mathematical Physics 36 (1995), S. 6611-6624 
    Details
    ISSN: 1089-7658
    Source: AIP Digital Archive
    Topics: Mathematics , Physics
    Notes: The sequences of supersymmetry for a cyclic adiabatic evolution governed by the supersymmetric quantum mechanical Hamiltonian are revised. The condition (so-called supersymmetric adiabatic evolution condition) under which the supersymmetric reductions of Berry (nondegenerated case) or Wilczek–Zee (degenerated case) phases of superpartners are taking place is pointed out. The analog of the Witten index (supersymmetric Berry index) is determined. The final expression for the new index has compact form of indBH=sDet U≡Det Uτ, where U is the cyclic evolution operator generated by supersymmetric Hamiltonian H and τ is a supersymmetric involution. As the examples of the suggested concept of the supersymmetric adiabatic evolution the holomorphic quantum mechanics on a complex plane and meromorphic quantum mechanics on Riemann surfaces are considered. The supersymmetric Berry indices for the models are calculated. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.531176
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  • 3
    Electronic Resource
    Electronic Resource
    Space charge fields in photorefractive crystals in the presence of direct current and alternating current fields: A new resonance (1996)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 68 (1996), S. 167-169 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: It is shown theoretically that the space charge field generated by two-wave mixing in a photorefractive crystal may have a resonant response when a dc field and a sinusoidal ac field are simultaneously applied. Resonance occurs when the frequency of the ac field is equal to the eigenfrequency of the space charge wave determined by the dc voltage. Analytical expressions are derived for the magnitude of the space charge wave and the optimum ratio of the ac to dc field is determined. The enhancement of the space charge field is shown to be considerably higher than that obtained by a nonresonant method utilizing a sinusoidal ac field alone. Under optimum conditions the maximum space charge field available is equal to mEq/2(square root of)2, where m is the modulation of the interference pattern and Eq is the saturation field. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.116448
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  • 4
    Electronic Resource
    Electronic Resource
    Electronic excitation of space charge waves in photorefractive materials (1996)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 69 (1996), S. 4265-4267 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The excitation of a space charge wave in a uniformly illuminated photorefractive crystal by an applied ac voltage is studied theoretically. A spatial differential equation for the ac component of the space charge field is derived and boundary conditions applicable both to Ohmic and rectifying junctions are obtained leading to an analytical solution for the space charge wave amplitude. It is shown that the low frequency space charge wave associated with the recharge of impurities can be efficiently excited with an amplitude approximately equal to the applied ac field. For the parameters of a BSO crystal, the space charge wave region declines within a few grating spacings near the cathode. The possibility of experimental observation of the effect is discussed. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.116966
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  • 5
    Electronic Resource
    Electronic Resource
    Energy relations for space-charge waves in photorefractive materials (1996)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 68 (1996), S. 3826-3828 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: An energy balance equation is derived with the aid of a partial differential equation describing the space-charge field in photorefractive materials. Expressions are found for power flux, losses, and the power absorbed from an external source both for the low- and high-frequency branches of space-charge waves. The efficiency of energy conversion from the external source into the space-charge wave is calculated and compared for two different mechanisms of optical excitation: (i) by a moving interference pattern and (ii) by a combination of a stationary interference pattern and an external ac field. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.116630
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  • 6
    Electronic Resource
    Electronic Resource
    Phase diagram of water in the vicinity of the triple point (1996)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 105 (1996), S. 3722-3725 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The melting curves of ice VI and ice VII were measured using a diamond-anvil pressure cell up to P=2.8 GPa and T=400 K and their metastable extensions. We found the existence of the metastable extension of the phase boundary between ice VI and liquid water within the stable region of ice VII and confirmed the presence of the metastable extension of the phase boundary between ice VII and liquid water within the stable field of ice VI. We found that the curvature of the ice VI–ice VII phase boundary is more pronounced than previously reported. The complete interpretation of our results might be made on the basis of thermodynamics of liquids in small confining systems. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.472191
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  • 7
    Electronic Resource
    Electronic Resource
    Enantioselective Intramolecular Cyclopropanations of Allylic and Homoallylic Diazoacetates and Diazoacetamides Using Chiral Dirhodium(II) Carboxamide Catalysts (1995)
    s.l. : American Chemical Society
    Journal of the American Chemical Society 117 (1995), S. 5763-5775 
    Details
    ISSN: 1520-5126
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/ja00126a016
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  • 8
    Electronic Resource
    Electronic Resource
    Highly selective enantiomer differentiation in intramolecular cyclopropanation reactions of racemic secondary allylic diazoacetates. (1995)
    s.l. : American Chemical Society
    Journal of the American Chemical Society 117 (1995), S. 11021-11022 
    Details
    ISSN: 1520-5126
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/ja00149a031
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  • 9
    Electronic Resource
    Electronic Resource
    Experimental observation of optical diffraction radiation (1998)
    Springer
    JETP letters 67 (1998), S. 802-807 
    Details
    ISSN: 1090-6487
    Keywords: 41.60.Ap ; 41.75.Ht
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The optical diffraction radiation of ultrarelativistic electrons at the boundary of a conducting medium is observed experimentally. Backward diffraction radiation, which, like transition radiation, is emitted at the angle of specular reflection from the target, is detected.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1134/1.567752
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  • 10
    Electronic Resource
    Electronic Resource
    Studies of an artificially generated electrode effect at ground level (1997)
    Springer
    Annales geophysicae 14 (1997), S. 1095-1101 
    Details
    ISSN: 0992-7689
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The outdoor experiments, using a metallic grid above the ground surface, have yielded well-defined vertical profiles of the space-charge density. The profiles showed strong evidence for the existence of an electrode effect, which could be named the artificial electrode effect and can serve as a very useful and well-controlled model for the study of atmospheric electric processes in the atmospheric surface layer. The build-up or break-down of an electrode-effect layer occurred in a time of the order of 10 s under the experimental conditions realized. The artificially generated electrode effect is dependent on the electrical field strength supplied, wind speed, turbulent mixing and ion mobilities. Wind speed and ion mobility seem to be the dominant factors, defining space-charge density profiles. A theoretical model for the artificial electrode effect has been developed, taking into account turbulent mixing of charged particles in the air flow with the logarithmic profile of the wind velocity. The numerical analysis of the boundary value problem for the two-dimensional equations for the light ion concentrations has been performed. The model presented shows a qualitative agreement of calculated space-charge profiles with measured ones, and explains the dependence of the artificial electrode effect on the dominant control parameters. The limiting conditions for the developed theory are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s00585-996-1095-2
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