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  • 1990-1994  (3)
  • 32.80.Rm  (2)
  • 07.80  (1)
  • 1
    ISSN: 1432-0649
    Keywords: 32.30.—r ; 32.80.Rm ; 32.80.Dz ; 35.10.Hn
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Resonance ionization mass spectroscopic (RIMS) measurements for trace analysis and spectroscopy of 237Np, the ecologically most important isotope of neptunium, are described. The chemical procedure for the separation of neptunium from aqueous samples as well as the preparation of filaments for RIMS are outlined. Several two- and three-step excitation schemes have been investigated in order to find suitable conditions for the sensitive detection of 237Np. Using a three-step, three-color excitation and ionization scheme an overall detection efficiency of 3×10−8 was obtained, resulting in a detection limit of 4×108 atoms (160 fg) of 237Np. The hyperfine structure splittings of the levels under investigation, which influence the detection limit, were measured. A new method to determine the first ionization potential (IP) was applied to neptunium yielding a value of IP=6.2655(2) eV.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-0649
    Keywords: 07.77 ; 07.80 ; 32.80 F ; 14.60
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We report here on the development of a high-temperature laser ion source useful for trace analysis and other applications. It consists of a high temperature ionization chamber, three tunable dye lasers pumped by copper vapor lasers for stepwise resonant ionization and a Mattauch-Herzog mass spectrometer for the analysis of photo-ions. The principle of the laser ion source and its theoretical efficiency are discussed, where the efficiency of a laser ion source is the ratio of photo-ions extracted out to the number of atoms introduced into the cavity. Experimentally, an efficiency of 2×10−3 has been achieved for technetium. The scheme of gated detection is described which is used for suppressing isobaric background of molybdenum. The possible improvements are briefly mentioned for achieving isotopic analysis of 108 atoms of 97,98Tc in the presence of 1015 atoms of molybdenum, as separated chemically from molybdenum ore. Such an analysis of technetium isotopes produced in molybdenite ore by a (v,e −) reaction, is expected to yield information about the solar neutrino flux.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1434-6079
    Keywords: 32.70.Fw ; 32.80.Rm
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Lifetimes of Rydberg states of the triplet-series 5s ns 3 S 1 withn = 19–23, 35 and 5s nd 3 D 3 withn = 18–20, 23–28 in the spectrum of neutral strontium have been determined. Observation of the exponential decay after excitation by a pulsed laser in a fast atomic beam and subsequent state-selective field ionization was employed. The lifetimes of the states of the3 S 1-series show the expectedn*3 dependence on the effective principal quantum number, while the3 D 3-series is disturbed by configuration mixing. Furthermore, state re-populations induced by black-body radiation have been observed.
    Type of Medium: Electronic Resource
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