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  • Electronic Resource  (3)
  • 1970-1974  (3)
  • 1973  (3)
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  • Electronic Resource  (3)
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  • 1970-1974  (3)
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  • 1
    Electronic Resource
    Electronic Resource
    Optical pumping of ions in buffer gases (1973)
    Springer
    The European physical journal 259 (1973), S. 371-390 
    Details
    ISSN: 1434-601X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Transient signals measured with a pulsed rf-optical pumping method are used to determine longitudinal relaxation rates for Sr+ ions (even isotopes) in noble gas buffers. Depolarization cross sections of the electronic spin in the Sr+52 S 1/2 ground state for binary collisions with rare gas atoms are deduced. The results for σ(Sr+52 S 1/2) in Å2 are (at temperatures between 374 and 449 °K): 2·10−5(He),4·10−5(Ne), 5.7·10−3(Ar), 1.8·10−2(Kr), and 4.0·10−2(Xe). These cross sections for the Sr+ ion are about two to three orders of magnitude larger than the corresponding ones for the isoelectronic neutral Rb atom. The large increase of the Sr+ relaxation rates is explained with the relaxation mechanism of spin-orbit coupling, taking into account two “indirect” effects of the ionic charge: the increase in the gas kinetic cross sections and the more intimate collisions of the Sr+ ion with the noble gas atoms. The depolarization is shown to be predominantly due to short-range interactions. A contribution to the relaxation of the Sr+ ion from Sr+-noble gas molecule formation, induced by three-body or resonant two-body collisions, could not be established for applied pressuresp between 1.5 and 15 Torr of Ar, Kr, and Xe.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01397375
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Optical pumping of ions in buffer gases (1973)
    Springer
    The European physical journal 260 (1973), S. 341-350 
    Details
    ISSN: 1434-601X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Optical pumping with the D2 resonance line can result in a zero2 S 1/2 ground state polarization at a particular buffer gas pressurep 0. For the even isotopes of Sr+ ions, the corresponding relaxation rate Γ1 of the dipolar polarization in the2 P 3/2 excited state can be calculated as a function of the mean lifetime τ of this state directly from the condition of zero2 S 1/2 ground state polarization. The calculation includes the branching decays of the 52 P 3/2 state to the 52 S 1/2 and 42 D 5/2,3/2 states, the collisional quenching from2 P and2 D states, and the diffusion of the Sr+ ions. From the calculated relaxation rate Γ1 and the measured value ofp 0, the cross sections for the destruction of the dipolar polarization in the2 P 3/2 state are obtained, σ1(Sr+52 P 3/2) in Å2: 72±9(He), 80±10(Ne), 124±15 (Ar), 148±18 (Kr), and 196±23 (Xe). The values of σ1 for the Sr+ ion are of comparable magnitude to those for the isoelectronic Rb atom.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01397958
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Relaxation and deorientation of110Ag(T 1/2=24.4s) nuclei produced by capture of polarized neutrons in the silver halides (1973)
    Springer
    The European physical journal 262 (1973), S. 189-210 
    Details
    ISSN: 1434-601X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Polarized110Ag nuclei are produced in the silver halides by capture of polarized neutrons at temperatures below 30 K and magnetic field strengths up to 6 kOe. The depolarization process is studied by observation of the β decay asymmetry as a function of magnetic field, temperature and of the radio frequency field strength in NMR signals. The depolarization is caused by a field dependent deorientation process and by temperature dependent spin-lattice relaxation. The deorientation is due to a succession of coupling steps of the nuclear spin with electromagnetic fields of defects generated as a consequence of the capture process, and the field dependence of the polarization can be understood as a decoupling curve. The temperature dependence of the spin-lattice relaxation is in accordance with the theory of quadrupolar relaxation above 18 K if an empirical phonon spectrum is used for the calculation. At lower temperatures the experimental relaxation rate is anomalously high, which may be due to resonance modes connected with recoil lattice defects.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01391836
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    Paper (German National Licenses)
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