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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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  • 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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  • 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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  • 4
    Electronic Resource
    Electronic Resource
    Relaxation phenomena and nuclear magnetic resonance of116In(T 1/2=14s) produced by capture of polarized neutrons in the indium III–V compounds (1971)
    Springer
    The European physical journal 244 (1971), S. 289-311 
    Details
    ISSN: 1434-601X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Polarized116In nuclei have been produced by capture of polarized thermal neutrons in several In compounds. At temperaturesT below 77 °K and magnetic field strengthsH 0 of several kOe, asymmetries of a few percent of the β− decay of the116In ground state could be observed in polycrystalline InP, InAs and InSb, thus indicating the nuclear polarization. Nuclear magnetic resonance signals have been measured with the result for the magnetic moment μ i (116In)=2.7723 (10) nm (uncorrected). β− decay asymmetry and spin lattice relaxation timeT 1 have been studied as a function ofH 0 andT. The effect ofH 0 is to decouple the hyperfine interaction caused by the capture-γ recoil process. However,H 0 has no influence uponT 1, which demonstrates the absence of nuclear relaxation due to paramagnetic impurities.T 1 is determined by quadrupolar relaxation. A quadrupole momentQ(116In)=0.09 (2) b was calculated by comparison of the116In relaxation rates with those of the stable115In isotope in the same compounds. Above 30 °K the temperature dependence of 1/T 1 agrees with a recent theoretical investigation. Below 30 °K the relaxation rate shows an anomalous behaviour, which can be explained by resonance modes due to recoil lattice defects.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01396789
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  • 5
    Electronic Resource
    Electronic Resource
    Correlation of electron spin resonance and optical absorption of K atoms in solid Ar (1987)
    Springer
    The European physical journal 67 (1987), S. 531-539 
    Details
    ISSN: 1434-6036
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Electron spin resonance (ESR) and optical absorption spectra of K atoms embedded in Ar matrices have been measured simultaneously. ESR and optical spectra could be correlated comparing the effects of annealing and light induced site modifications. Electron spin relaxation times were estimated by saturation measurements. A large variety of ESR spectra was found which could be arranged into four groups according to their A and g factor matrix shifts. Two of these groups could be correlated with optical absorptions namely with the so-called red and blue triplet bands. The other two groups belong to K-(H2O)n complexes. Part of the absorption disappeared irreversibly upon annealing at about 12 K. There is considerable experimental evidence that this annealing process indicates the transition from an amorphous to a microcrystalline structure at about 12 K.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01304125
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  • 6
    Electronic Resource
    Electronic Resource
    Vorkommen von phosphororganischen Insecticiden im Fetus (1970)
    Springer
    Archives of toxicology 26 (1970), S. 17-22 
    Details
    ISSN: 1432-0738
    Keywords: Organophosphate Insecticides ; Fetus ; Phosphororganische Insecticide ; Fetus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Nach Applikation von Methylparathion, Bromophos und Imidan an trächtige Albinoratten sind diese Wirkstoffe in der Placenta sowie in Leber, Gehirn und Muskelgeweben der Feten nachweisbar. Das PO-Isologe konnte beim Methylparathion in allen untersuchten embryonalen Geweben festgestellt werden. Bei den mindertoxischen Insecticiden Bromophos und Imidan war lediglich das PO-Isologe des Bromophos, das Bromoxon, in Spuren im Muskelgewebe der Feten nachweisbar.
    Notes: Summary Following application of Methylparathion, Bromophos and Imidan in pregnant albino rats, these compounds are detectable in the placenta as well as in the liver, brain and muscle tissue of the fetus. The organophosphate isologe of Methylparathion could be found in all embryonic tissue studied. By the less toxic insecticides Bromophos and Imidan, only traces of the Bromophos isologe Bromoxon could be detected in the muscle tissue of the fetus.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00577963
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  • 7
    Electronic Resource
    Electronic Resource
    Stenosis and occlusion of the subclavian artery: ultrasonographic and clinical findings (1987)
    Springer
    Journal of neurology 234 (1987), S. 396-400 
    Details
    ISSN: 1432-1459
    Keywords: Subclavian steal syndrome ; Vertebrobasilar insufficiency ; Doppler sonography ; Atherosclerosis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Continuous-wave (CW) Doppler sonography has proved to be a reliable tool both to detect subclavian stenosis or occulusion and to detect reversal of blood flow in the vertebral artery. This method is entirely atraumatic and in contrast to angiography allows investigation of asymptomatic patients and provides more representative data for epidemiological studies. The incidence of subclavian stenosis or occlusion was 1.15% among the 23,500 patients examined in our department between 1978 and 1985. Of the 272 patients with unilateral or bilateral subclavian stenosis or occlusion, 54% were asymptomatic with no subjective complaints and were normal upon neurological examination; 29% reported vertebrobasilar transient ischaemic attacks (TIAs), with or without concomitant TIAs or infarction in the vascular territory of the carotid arteries; and 17% complained of symptoms exclusively referring to the region of carotid blood supply. Reversal of blood flow in the ipsilateral vertebral artery was detected in 152 patients (56%). The incidence of neurological symptoms within this group was double that found in patients without steal. None of the patients suffered from permanent vertebrobasilar damage. In most cases, subclavian artery disease was due to atherosclerosis. For 13 patients an inflammatory, iatrogenic, traumatic, or congenital aetiology could be assumed. The marked preponderance of left-sided subclavian stenosis or occlusion, reported by others, could be confirmed among our patients, but was less pronounced for tight stenoses than for occlusions. Mild-to-moderate subclavian stenoses were about equally distributed on each side.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00314084
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  • 8
    Electronic Resource
    Electronic Resource
    Optical pumping of free atomic ions with hyperfine structure (1970)
    Springer
    The European physical journal 236 (1970), S. 97-100 
    Details
    ISSN: 1434-601X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Free atomic ions with hyperfme structure have been oriented m He buffer gas by absorption of circularly polarized light. ΔF=±1 hyperfine transitions have been measured in the 62 S 1/2 ground state of135Ba+ and137Ba+ with an accuracy of 1 part in 107.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01394885
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  • 9
    Electronic Resource
    Electronic Resource
    Elektrische Quadrupolwechselwirkungen von20F im MgF2-Einkristall (1974)
    Springer
    The European physical journal 269 (1974), S. 47-57 
    Details
    ISSN: 1434-601X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Polarized20F nuclei (T 1/2=11s,I=2) have been produced in a tetragonal MgF2 single crystal by capture of polarized neutrons. Nuclear magnetic resonance transitions have been induced and observed via the asymmetricΒ decay to20Ne, yielding the quadrupole coupling constant ¦e 2 q Q/h¦=5.77(2)MHz, the quadrupole moment ¦Q(20F)¦=0.064(12) b and the asymmetry parameter of the electric field gradientη=0.317(2). In order to study possible lattice defects produced by the recoil displacement due to the captureγ-rays NMR signals were registered both at room temperature and at 12 K. Width and depth of the resonance curves indicated that at room temperature nearly all20F ions occupy normal lattice sites with an undisturbed environment. At 12 K, however, where no annealing occurs, this is only true for about half of the20F ions which are stopped directly at defect free sites. The other half of the20F ions at 12 K shows resonance frequencies shifted by defect interactions up to the order of some 100 kHz. Furthermore two simple methods are reported which allow a quick estimate of the strength of the quadrupolar interaction: (1) observation of theΒ decay asymmetry versus the magnetic field strength (decoupling curve), (2) broad-band modulation of the inducedrf field and observation of theΒ asymmetry versus the depth of the modulation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01668868
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  • 10
    Electronic Resource
    Electronic Resource
    Site modification of K atoms in solid Ar by X-ray and light irradiation (1987)
    Springer
    The European physical journal 4 (1987), S. 373-378 
    Details
    ISSN: 1434-6079
    Keywords: 61.80 ; 78.40 ; 71.35
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The influence of X-ray irradiation on the optical absorption of K-atoms in Ar-matrices was studied as a function of time and temperature. Exponential decrease of the so-called red and blue triplet absorptions was observed. Simultaneously a new absorption in the range of the red triplet was built up. The new absorption could alternatively be produced by light irradiation into the red or the blue triplet, as was shown in a second experiment studying correlated optical and ESR-absorption. After annealing at 15 K the new absorption disappeared, and the original absorptions were largely restored. All experimental results can well be understood in terms of exciton production, self-trapping, and deexcitation, and are described by a master equation system.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01384890
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