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  • 1985-1989  (5)
  • 1980-1984  (7)
  • 1975-1979  (2)
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  • 1
    Electronic Resource
    Electronic Resource
    Electronic rearrangement on molecules accompanyingβ-decay investigated by nuclear resonance fluorescence (1983)
    Springer
    The European physical journal 311 (1983), S. 253-257 
    Details
    ISSN: 1434-601X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Using gaseous60CoI2 sources, the velocity distribution of60Ni nuclei afterβ-decay of60Co has been measured by the nuclear-resonance-fluorescence coincidence (NRFC) method. By comparison with model calculations, information is obtained on the rearrangement of electrons on the molecule as a consequence of the change of nuclear charge. In 42% of the rearrangement processes bound (NiI2)+ or (NiI)+ molecule ions are formed. In 24% the molecule is singly charged but with the bonds between Ni and its molecular partners ruptured. In 34% the charging of more than one molecular partner leads to Coulomb explosion of the molecule. The probability of finding more than one charge on the molecule is larger by a factor of 2 as compared to the probability for electron shake-off on an isolated Ni atom.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01415678
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Stopping of slow recoil atoms in gases (1981)
    Springer
    The European physical journal 301 (1981), S. 101-107 
    Details
    ISSN: 1434-601X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Nuclear Resonance Fluorescence spectra contain information on the slowing-down behaviour of recoiling atoms in the energy range pertinent to the specific reaction. On the basis of conventional transport theory, measured spectra for arsenic atoms with energies ≲15 eV slowing down in helium are analysed. The assumption of continuous slowing down turns out to be well justified, and the thermal motion of the gas atoms is shown to influence the effective stopping power only slightly. Somewhat surprising in view of uncertainties concerning the charge state of the recoiling atoms, theoretical predictions based on Lenz-Jensen elastic interaction agree well with the measured spectra. At present, the experimental data do not allow direct inversion, but the calculated spectra are shown to depend sensitively on the stopping-power input.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01419238
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    The slowing-down of low-energy recoil atoms in solids and liquids investigated by nuclear resonance fluorescence (1987)
    Springer
    The European physical journal 66 (1987), S. 147-151 
    Details
    ISSN: 1434-6036
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Using the nuclear resonance-fluorescence technique, the slowing down mechanisms of recoiling140Ce nuclei in La, LaMg3 and La2O3, are studied via the Dopler shift of the 1.596 MeV γ transition, following the β decay of140La. In LaMg3 the slowing down time shows a pronounced temperature dependence with a sharp drop close to the melting point. In the oxide, as well as in the metal with only a small oxygen content, the slowing down time is considerably smaller than in the pure metal. These results are in support of a model, describing the slowing down process in solids in terms of a damped oscillation, with a time dependence related to the phonon frequency spectrum.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01311649
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  • 4
    Electronic Resource
    Electronic Resource
    Dependence of the nuclear recoil motion on the phonon spectrum of solids investigated by nuclear resonance fluorescence (1984)
    Springer
    The European physical journal 55 (1984), S. 287-291 
    Details
    ISSN: 1434-6036
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The time dependence of the recoil velocity of a140Ce nucleus in a La and a LaF3 lattice after β emission is studied via the Doppler shift of the 1.596 MeV γ transition in140Ce. Evidence is obtained that the nucleus does not leave the lattice site even at a recoil energy of about 20 eV but carries out a damped oscillation. The quantitative comparison of the recoil velocity with the predictions of lattice theory leads to partial agreement.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01304079
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  • 5
    Electronic Resource
    Electronic Resource
    Nuclear resonance fluorescence in124Te and126Te: Vacancy cascades in molecules (1976)
    Springer
    The European physical journal 279 (1976), S. 19-25 
    Details
    ISSN: 1434-601X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Using gaseous sources of I2 and HI containing the radioactive isotopes124I and126I effective cross sections for nuclear resonance scattering from the first 2+ states of124Te and126Te were measured. Information is obtained about the charging of the nonradioactive molecular partner afterEC decay, the interaction of highly charged ions with neutral molecules, and the slowing down of atoms in a Xe buffer gas. Indications of an iodine complex being stable in the gaseous phase are found.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01409087
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    Paper (German National Licenses)
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  • 6
    Electronic Resource
    Electronic Resource
    The slowing down of atoms with kinetic energies ofW≲5 eV in Noble Gases: Evidence for inelastic interactions (1979)
    Springer
    The European physical journal 289 (1979), S. 365-371 
    Details
    ISSN: 1434-601X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Profiles of the 264.6 keVγ-line of75As emitted after the electron capture decay of75Se have been measured using nuclear resonance fluorescence in combination withγγ-coincidences as a high resolution, variable-energyγ spectrometer. The sources consisted of gaseous75SeH2 with different amounts of Kr or Xe. From the line profiles information has been obtained about the velocity distribution of the radioactive75As ions after electron capture decay and about the slowing down of the75As ions in the moderator gas. The75As ions obtain kinetic energies of up toW∼5 eV by neutrino recoil and Coulomb fragmentation of the75SeH2 molecules, corresponding to velocities of the order of 105 cm s−1. The slowing down of the75As ions has been interpreted in terms of the model of colliding elastic spheres, taking into account the thermalization in an exact way. No satisfactory agreement has been obtained between measured and calculated line profiles. This result indicates that inelastic processes are of great importance in the interaction of75As ions or atoms with the noble gas moderator atoms.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01409387
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    Paper (German National Licenses)
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  • 7
    Electronic Resource
    Electronic Resource
    The stopping of slow75As recoil atoms in He, Ne and H2 (1982)
    Springer
    The European physical journal 306 (1982), S. 301-306 
    Details
    ISSN: 1434-601X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The slowing down of75As recoil atoms with energies ≲10eV in He, Ne and H2 was investigated by measuring Doppler-widened line profiles of the 265 keV gamma line emitted by the recoil nuclei. The line profiles contain information on the stopping powers of gases for heavy ions with initial velocities υ≲3·105 cms−1. They are analyzed in terms of the continuous slowing down theory developed by Falcone et al. The profiles observed with He and Ne are well described by assuming the stopping power to be based on Lenz-Jensen elastic interaction between recoil and moderator atoms. The profiles observed with H2 do not agree with predictions based on that interaction. The stopping power of H2 for the75As recoil atoms is found to be larger than that of He.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01432370
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  • 8
    Electronic Resource
    Electronic Resource
    Pressure-dependent perturbed directional correlations and collision cross sections in the meV and eV energy region for gaseous ion — Noble gas systems (1983)
    Springer
    Hyperfine interactions 15 (1983), S. 173-176 
    Details
    ISSN: 1572-9540
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Conclusions The new experimental results for pure H 2 75 Se complete the measurements of gaseous H 2 75Se-sources with different buffer gases. The extended theory produces a good fit to all experimental points and provides the foundation for interpreting the estimated collision cross sections as depolarization or charge transfer cross sections.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02159734
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  • 9
    Electronic Resource
    Electronic Resource
    Measurement of the hyperfine interaction of free75As ions In H2, He, Ne, Kr and Xe buffer environments and estimate of clolision cross sections in the eV and meV energy region (1983)
    Springer
    Hyperfine interactions 13 (1983), S. 297-305 
    Details
    ISSN: 1572-9540
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract With the time-integral perturbed angular correlation (TIPAC) method the pressure dependence of the perturbation of the 121.1–279.5 keV γ-γ cascade in75As has been investigated using gaseous H2 75Se sources in different buffer environments. The obtained attenuation coefficients G22 (∞) in the range of 0.55 to 1.0 were fitted with a theoretical stochastic model. In the region of low density, where the correlation time τC is large compared to the lifetime τ of the intermediate level of the nucleus, charge transfer collision cross sections have been evaluated between 8.1·10−16 cm2 for He, 1.3·10−14 cm2 for Xe and 1.8·10−14 cm2 for the molecular H2 buffer gas. For increasing densities of the buffer gases the correlation time τC became small compared to the intermediate lifetime τ. The main effect in this region is the depolarization, and we found cross sections between 5.2·10−15 cm2 for He, 8.7·10−14 cm2 for Xe and 1.2·10−13 cm2 for the H2 buffer gas.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01027259
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    Paper (German National Licenses)
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  • 10
    Electronic Resource
    Electronic Resource
    Magnetic hyperfine interaction after77Br implantation into iron (1988)
    Springer
    Hyperfine interactions 39 (1988), S. 81-91 
    Details
    ISSN: 1572-9540
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Radioactive77Br ions were implanted at 60 keV and 270 keV into polycrystalline iron foils. The magnetic hyperfine interaction of the daughter nucleus77Se in the 250 keV isomeric level was investigated using the perturbed angular correlation technique and fast BaF2 detectors. The Larmor frequency at room temperature was determined as ωL=1272(2) MHz, leading to a substitutional hyperfine field ofB hf(SeFe)=62(6) T. The substitutional fraction rises from 21% at room temperature to about 100% at 790 K annealing temperature. No other well-defined magnetic or electric hyperfine component attributable to impurity-defect complexes was identified. The diffusion of Br atoms in the surface region during the annealing process was studied via Rutherford backscattering with 1.0 MeV α-particles.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02394648
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