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  • 1
    Electronic Resource
    Electronic Resource
    Low-level copper concentration measurements in silicon wafers using trace-element accelerator mass spectrometry (1998)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 72 (1998), S. 3008-3010 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Accelerator mass spectrometry (AMS) is now widely used in over 30 laboratories throughout the world to measure ratios of the abundances of long-lived radioisotopes such as 10Be, 14C, 36Cl, and 127I to their stable isotopes at levels as low as 10−16. Trace-element AMS (TEAMS) is an application of AMS to the measurement of very low levels of stable isotope impurities. Copper concentrations as low as 1 part per billion have been measured in silicon wafers. In this letter, we demonstrate the use of TEAMS to measure previously unknown copper concentration depth profiles in As-implanted Si wafers at a few parts per billion. To verify the TEAMS technique, the samples from the same wafer were measured with secondary ion mass spectrometry, which showed the same profiles, albeit plateauing out at a concentration level six times higher than the TEAMS measurement. The ability to measure at these levels is especially significant in light of the recent moves towards the use of copper interconnects in place of aluminum in integrated circuits. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.121523
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  • 2
    Electronic Resource
    Electronic Resource
    Reactions of Titanium-Carbon Cluster Cations with Acetone: New Evidence for the Stability of the Met-Cars (1995)
    s.l. : American Chemical Society
    Journal of the American Chemical Society 117 (1995), S. 4026-4029 
    Details
    ISSN: 1520-5126
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/ja00119a017
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Identification of 209Hg (1998)
    Springer
    The European physical journal 2 (1998), S. 5-7 
    Details
    ISSN: 1434-601X
    Keywords: PACS:25.70.Hi Transfer reactions – 27.80.+w 190 ≤ A ≤ 219
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract: The new neutron-rich nuclide 209Hg has been identified for the first time. An on-line, gas-thermochromatographic technique was developed for rapidly separating the Hg-element products from 600-MeV 18O+ nat Pb(thick target) reaction system. A special detection arrangement was used in order to detect the weak γ-activities of the neutron-rich Hg isotopes. The half-life of 209Hg was determined to be 35−6 +9 s.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s100500050082
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  • 4
    Electronic Resource
    Electronic Resource
    Characterization of the KNSBN: Cu crystal with two-wave coupling at visible and infrared wavelengths (1995)
    Springer
    Applied physics 61 (1995), S. 207-211 
    Details
    ISSN: 1432-0649
    Keywords: 42.70.Gz ; 42.30.Va ; 42.40.Kw ; 42.65
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We have optically characterized the newly-developed photorefractive crystal KNSBN: Cu by two-wave coupling at visible and near-infrared wavelengths. The effective electrooptic coefficientsξ(k g)r 13 andξ(k g)r 33, the effective charge carrier densityN eff, the dark conductivityσ d, the product of mobility and electron-trap recombination timeμτ R, the formation and decay rate of index grating and the absorption coefficientα of the crystal were determined from visible to near-infrared wavelengths. Their wavelength dependences were also studied. It is interesting to notice that the KNSBN: Cu crystal has a very largeN eff and large gain coefficientΓ for ordinary ray (o-ray) in the visible region, and the photorefractive properties of the crystal are very different in the visible and near-infrared spectral regions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01090945
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  • 5
    Electronic Resource
    Electronic Resource
    Divergence of mycorrhizal fungal communities in crop production systems (1995)
    Springer
    Plant and soil 170 (1995), S. 131-140 
    Details
    ISSN: 1573-5036
    Keywords: crop productivity ; cropping systems ; Glomales ; soil ecology ; vesicular arbuscular mycorrhizal fungi
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Mycorrhizal fungi are present in all arable soils and colonize nearly all crops and weed pests of crops. They may be involved as mutualists or pathogens of crops in well known but poorly understood phenomena such as crop rotation and green manure effects on soil productivity. Crop change effects on mycorrhizal fungal community parameters were evaluated in three field experiments. In Experiment 1, soybean (Glycine max (L.) Merr. cv. Douglas) was grown continuously or rotated with corn (Zea mays L.), milo (Sorghum bicolor (L.) Moench), or fescue (Festuca arundinacea Schreb cv. Johnstone) for two years, then soybean was grown on all plots. Continuous soybean plots were dominated byGigaspora spp., while rotated crops were dominated byGlomus spp. Differences in communities and community indices of continuous soybean and rotated plots were reduced after growing soybeans on rotated plots. In Experiment 2, a fescue sod was plowed and pearl millet (Pennisetum americanum Leeke) or crabgrass (Digitaria sanguinalis (L.) Scop.) grown. Both hosts resulted in great changes in populations of individual species, decreases in community dominance, and increases in community diversity and equitability. Crabgrass also resulted in reduced species richness. In Experiment 3, tobacco (Nicotiana tabacum L.) or fescue was planted on adjacent tracts of land with a long-term history of either fescue (30 yr) or sorghum-sudangrass (Sorghum bicolor (L.) Moench. ×S. sudanense (Piper) Staph.) (3 yr). The long-term cropping history had major effects on the mycorrhizal fungal communities which were related to the expression of mycorrhizal stunt disease of tobacco. Changes occurred in these communities in response to either current-season crop. These experiments suggest that crop rotation causes large changes in mycorrhizal fungal communities, that these changes may be involved in the rotation effect on soil productivity, and that design of cropping systems should take mycorrhizal fungal communities into consideration.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02183061
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    Paper (German National Licenses)
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