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  • 1
    Electronic Resource
    Electronic Resource
    Differential cross section measurements for Na-Ar and Na-Ne scattering: A test of interaction potentials (1983)
    Springer
    The European physical journal 312 (1983), S. 271-276 
    Details
    ISSN: 1434-601X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Differential cross sections for elastic scattering of Na(3s) from Ar and Ne were measured with an angular resolution of 0.1° in a range of relative energies between 5 and 20×10−14 erg. Excellent agreement is found between our experimental data for the Na-Ar system and calculated scattering patterns based on a model potential given by Düren et al. [3] with a well depth of ɛ=0.82×10−14 erg and an equilibrium distancer m =5.09×10−8 cm. The spectroscopically determined potential of Tellinghuisen et al. [9] is less suited to interpret our measurements; its repulsive branch has to be shifted to largerr-values by about 0.05×10−8cm. By comparing our Na-Ne measurements with calculations based on model potential of Masnou-Seeuws et al. [7] and of Peach [6] we find that both potentials are too soft in their repulsive part. The best fits to our measurements are obtained with an empirical potential with ɛ=0.16×10−14 erg, as obtained from spectroscopic data,r m =5.35(5)×10−8cm and a repulsive part which is significantly steeper than obtained from model potential calculations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01414053
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  • 2
    Electronic Resource
    Electronic Resource
    Influence of “travelling velocities” on molecular autoionization electron spectra (1982)
    Springer
    The European physical journal 307 (1982), S. 41-49 
    Details
    ISSN: 1434-601X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We present electron energy spectra that arise in Li+ —He collisions in the laboratory collision energy range from 1.4 to 3 keV, and that are observed at 0° and 180° with respect to the Li+ beam. The spectra are composed of a component due to atomic autoionization of doubly excited He in the field of Li+, and a component due to molecular autoionization of the collision system. The variation of the latter component with collision energy and observation angle is analyzed in terms of a newly developed spectral shape function for molecular autoionization that implies a “distribution of travelling velocities” of the collision system during electron emission. From the comparison of calculated and measured spectra it is concluded that the physical interpretation on which the analysis is based is correct. Two parameters of the distribution of travelling velocities are determined.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01416071
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  • 3
    Electronic Resource
    Electronic Resource
    Quasimolecular or kinematical broadening of autoionization electron spectra from Li+/He collisions? a coincidence study (1985)
    Springer
    The European physical journal 320 (1985), S. 81-88 
    Details
    ISSN: 1434-601X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We have measured energy- and angular distributions of autoionization electrons from Li+/He collisions in coincidence with the scattered Li+ projectiles. The coincident energy spectra do not exhibit the broad structures that are observed in the non coincident spectra and which in the past were attributed to quasimolecular autoionization of the (LiHe)+ system. We show that these broad structures are caused by kinematical shifts of electron spectra from pure atomic autoionization following different scattering events. With an exploitation of published inelastic differential scattering cross sections and with the assumption that the angular electron distribution with respect to the asymptotic internuclear line is nearly independent of the scattering angle we are able to reproduce the non coincident electron spectra satisfactorily.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01411928
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  • 4
    Electronic Resource
    Electronic Resource
    Observation of instabilities in a Paul trap with higher-order anharmonicities (1995)
    Springer
    Applied physics 61 (1995), S. 277-283 
    Details
    ISSN: 1432-0649
    Keywords: 32.80
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Systematic measurements of the relative ion number stored in a Paul trap within the stability diagram given by the solution of the equation of motion reveal many lines, where only few or no ions can be confined. The observations can be explained by the presence of perturbations from higher-order components in the trapping potential, which is a quadrupole potential in the ideal case. The resonances follow the equation (n r /2)β r + (n r /2)β z = 1,n r +n z =N, where 2N is the order of the perturbation,n r ,n z are integer andβ r ,β z are stability parameters of the trap. The experiments were performed on H+ and H 2 + ions, which are detected after a storage time of 0.3 s by ejection from the trap.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01082047
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  • 5
    Electronic Resource
    Electronic Resource
    Formation of hollow atoms at metal- and insulator surfaces (1998)
    Springer
    Applied physics 67 (1998), S. 705-710 
    Details
    ISSN: 1432-0630
    Keywords: PACS: 34.70.+e; 79.20.Nc; 97.60.Bm
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003390050842
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  • 6
    Electronic Resource
    Electronic Resource
    The effect of electron-spin uncoupling on differential scattering cross sections for excited alkalirare gas systems (1985)
    Springer
    The European physical journal 320 (1985), S. 1-10 
    Details
    ISSN: 1434-601X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We have measured differential cross sections for the scattering of laser-excited Na(32 P 3/2) by Ne. The rapid oscillations in the experimental scattering patterns measured at high angular resolution cannot be explained semi-classically on the basis of the elastic approximation. We therefore apply a collision model proposed by MasnouSeeuws et al. [1] which takes into account the partial uncoupling of the electron-spin from the orbital angular momentum. The results obtained with this model are — for the first time — compared quantitatively with the result of a fully quantummechanical close-coupling calculation and with our experimental data. In both cases good agreement is found. This proves that the observed oscillatory structure is strongly influenced byΠ-∑ interferences which — due to spin uncoupling — do not cancel even if the scattering signals are summed over all final fine-structure states. Our semi-classical analysis is also applied to the Na(32 P 1/2)-Ar and K(42 P 3/2)-Ar scattering experiments reported by Düren et al. [2, 3]. The agreement with regard to the frequency of the oscillatory structure indicates that here too spin uncoupling causes theΠ-∑ interferences to appear in the differential cross sections.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01411920
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  • 7
    Electronic Resource
    Electronic Resource
    Neutralization of H-like ions at a W-surface: via auger cascades? (1991)
    Springer
    The European physical journal 21 (1991), S. S351 
    Details
    ISSN: 1434-6079
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We present the electron spectra for 07+ on a polycrystalline tungsten surface at collision energies between 100 eV and 100 keV. We find clearly resolved structures from projectile KLL-and LMM Auger electrons. The relative intensities of these peaks show that then=2 level is partly populated by ‘side-feeding’ processes. The time dependence of the KLL peak and the LMM peak can be described by a single exponential.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01426351
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  • 8
    Electronic Resource
    Electronic Resource
    He2+-H collisions: experimental charge exchange cross sections and their relevance for alpha particle diagnostics at JET (1991)
    Springer
    The European physical journal 21 (1991), S. S163 
    Details
    ISSN: 1434-6079
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We have determined absolute cross sections for electron capture into the quasi-degenerate4l states of He+ produced in collisions of He2+ on atomic hydrogen. The cross sections have been deduced by deconvoluting spatial HeII(n =4 →n=3) emission profiles. The measurements have been perfored in the impact energy range of 2−130 keV/amu. The results are compared with theory. In addition we discuss the relevance of these cross sections to α-particle diagnostics in fusion plasmas. At the JET tokamak the HeII(n=4 →n=3) emission can be used to determine related quantities like ion temperature, plasma rotation and local α-particle densities.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01426275
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  • 9
    Electronic Resource
    Electronic Resource
    Core-changing versus core-conserving charge transfer in Ne6+-He collisions (1991)
    Springer
    The European physical journal 21 (1991), S. S255 
    Details
    ISSN: 1434-6079
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We have measured VUV spectra of photons emitted by Ne5+* ions subsequent to single-electron capture in Ne6+- He collisions at impact energies of 1.2 and 0.11 keV/amu. Capture into the NeVI (1s 22s 23d) state has been identified as the dominant reaction channel at both energies. At 0.11 keV/amu capture into core-excited singlet states contributes 35% to the total cross section.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01426312
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  • 10
    Electronic Resource
    Electronic Resource
    Double electron capture into highly charged ions: correlated or independent? (1991)
    Springer
    The European physical journal 21 (1991), S. S285 
    Details
    ISSN: 1434-6079
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We propose an independent-electron model for describing quantitatively the population of doubly excited (n ℓ n ℓ′) states formed by two-electron capture into multiply charged ions. Population probabilities calculated by this model reproduce experimentally determined ones if one assumes that the classical electronic angular momentum is preserved, in magnitude and also in orientation. Correlation during the collision need not be invoked for the interpretation of the spectra.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01426325
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