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  • Szintillations-Spektrometrie  (3)
  • Analytical Chemistry and Spectroscopy  (2)
  • 12.20.Fv  (1)
  • 1
    Electronic Resource
    Electronic Resource
    Evidence for a resonance in positron-electron scattering at 810 keV centre-of-mass Energy (1988)
    Springer
    The European physical journal 330 (1988), S. 173-181 
    Details
    ISSN: 1434-601X
    Keywords: 13.10.+q ; 12.20.Fv ; 14.80.Pb
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract A monoenergetic positron (e +) beam (ΔT/T〈5·10−4) from the Stuttgart pelletron accelerator and a 4.6 mg/cm2 Be target has been employed to investigatee + e −scattering in the MeV region in a large solid angle with high statistics by means of a novel positionsensitive detector system. Superimposed on the Bhabha scattering, a structure has been found at ane + kinetic energy of 2263 keV (810 keV excitation energy in thee + e −rest frame). From the energy-integrated resonance cross-section of $$\sigma _{res} \cdot \Gamma _{res}^{e^ + e^ - } $$ ≅30 b·eV (c.m.) and the standard resonance cross-section we estimate partial resonance widths $$\Gamma _{res}^{e^ + e^ - } $$ ≅72 meV or 24 meV for total angular momenta J=0 or J=1, respectively. The structure, which has not been predicted within the framework of quantum electrodynamics, coincides with one of the sum energies of the correlatede + e −lines observed in heavy-ion collisions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01293393
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Determination of ethers and alcohols in reformulated gasolines by gas chromatography/atomic emission detection (1995)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 18 (1995), S. 108-110 
    Details
    ISSN: 0935-6304
    Keywords: GC/Atomic Emission Detection (GC/AED) ; Reformulated gasolines ; Selective analyses of oxygenates ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A GC method for the determination of oxygenated additives in reformulated gasolines (RFG) is described. The method uses on-column injection and atomic emission selective detection of oxygenates using the 777 nm NIR emission line. Detection limits are approximately 10 ppm oxygen. Results compared well with other techniques, such as GC/FTIR.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240180208
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  • 3
    Electronic Resource
    Electronic Resource
    Tritium in Lebensmitteln (1974)
    Springer
    Fresenius' Zeitschrift für analytische Chemie 272 (1974), S. 280-283 
    Details
    ISSN: 1618-2650
    Keywords: Best. von Wasserstoff-3 in Lebensmitteln, Wasser ; Szintillations-Spektrometrie ; Prüfung des Verfahrens
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Zur Prüfung der Tritiumbestimmungsmethode und zur Ermittlung der Tritiumaktivität wurden Lebensmittel bekannter Herkunft untersucht. Die Genauigkeit der Meßmethode über längere Zeit wird durch die statistische Auswertung der Nullwerte und Zählausbeuten bestätigt. Milch, Kartoffeln und Äpfel wiesen einen mittleren Gehalt von 600–800 pCi Tritium pro Liter Wasser auf. Trinkwasser enthielt dagegen in Abhängigkeit von der Herkunft als Grundoder Oberflächenwasser sehr unterschiedliche Tritiumaktivitäten. Lebensmittelproben aus dem Bereich von Kernreaktoren unterschieden sich im Tritiumgehalt nicht von solchen anderer Herkunft.
    Notes: Abstract In order to test the method of tritium determination and to determine the tritium activity, foods of known origin were investigated. The accuracy of the method over a prolonged period of time is confirmed by the statistical evaluation of the background values and of the counting efficiency. An average value of 600–800 pCi of tritium in one litre of water was found in milk, potatoes and apples. Drinking water contained very different activities of tritium, depending on its origin as ground or surface water. Food samples from the environment of nuclear reactors were not different in their tritium content when compared to those of other origin.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00431341
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    Tritium in foods (1974)
    Springer
    Fresenius' Zeitschrift für analytische Chemie 268 (1974), S. 109-113 
    Details
    ISSN: 1618-2650
    Keywords: Best. von Wasserstoff-3 in Lebensmitteln ; Szintillations-Spektrometrie ; Szintillations-Systeme f. d. Messung
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Es wurden die Eigenschaften ausgewählter Szintillationssysteme für die Messung sehr niedriger Tritiumgehalte in aus Lebensmitteln gewonnenen Wasserproben im Flüssigkeitsszintillationsspektrometer untersucht. Der Einfluß der Parameter der Meßmethode auf die Nachweisgrenze wurde über Wertziffern definiert. Optimale Werte wurden mit einem aus PPO, bis-MSB, p-Xylol und Triton N-101 bestehenden Emulsionssystem erhalten, das 40% Wasser aufnimmt. 0,16–0,18 pCi/ml Wasser sind mit diesem System noch nachweisbar. Tritium-armes Vergleichswasser wurde durch Verbrennung von Propan hergestellt.
    Notes: Abstract The qualities of selected scintillation systems for the measurement of very low tritium content in water samples from foods were investigated in the liquid scintillation spectrometer. The influence of the parameters of the measuring method on the detection limit was defined by figures of merit. Optimum values were obtained with an emulsion system, which consists of PPO, bis-MSB, p-xylene and Triton N-101, and which takes up 40% water. 0.16 to 0.18 pCi/ml water are detectable with this system. Reference water, which is poor in tritium, was produced by combustion of propane.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00431150
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  • 5
    Electronic Resource
    Electronic Resource
    Tritium in Lebensmitteln (1972)
    Springer
    Fresenius' Zeitschrift für analytische Chemie 261 (1972), S. 203-208 
    Details
    ISSN: 1618-2650
    Keywords: Best. von Tritium in Lebensmitteln ; Szintillations-Spektrometrie ; Verbrennungsapparatur und Wasserreinigungsanlage
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Zur Ermittlung des natürlichen Tritiumgehaltes von Lebensmitteln wurde eine Verbrennungsanlage entwickelt, in der aus Lebensmitteln beliebiger Zusammensetzung in einem Arbeitsvorgang etwa 100 ml Wasser gewonnen werden. Zur Messung der Tritiumaktivität dieses Verbrennungswassers im Flüssigkeitsszintillationsspektrometer wird das Wasser von störenden Verbrennungsprodukten durch Destillation gereinigt. Aufbau und Arbeitsweise der Verbrennungsanlage und des Wasserreinigungssystems werden beschrieben.
    Notes: Abstract To investigate the natural tritium content of foods a combustion apparatus was developed, in which nearly 100 ml of water are obtained in one operation from foods of any composition. To measure the tritium activity of this combustion water in the liquid scintillation spectrometer, the interfering combustion products are removed by distillation. The construction and operation of the combustion apparatus and of the water purification system are described.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00424284
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  • 6
    Electronic Resource
    Electronic Resource
    Structural study of surface tungstate in WO3—Al2O3: Effects of Hydration and 18O ExchangeReference in this paper to any specific product, process or service is to facilitate understanding and does not necessarily imply its endorsement or favoring by the United States Department of Energy. (1984)
    Chichester [u.a.] : Wiley-Blackwell
    Journal of Raman Spectroscopy 15 (1984), S. 282-287 
    Details
    ISSN: 0377-0486
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The Raman spectra of a series of WO3—AI2O3 catalysts containing 1-30 wt-% of WO3 were investigated with respect to the effect of O2 calcination and H2O—D2O exposure. These studies showed that the frequencies of bands due to surface tungstate species can be shifted reversibly by as much as 6% of their values during alternate O2 calcination and H2O exposure cycles. The exchange of 18O for l6O in the surface tungstate was also investigated with Raman spectroscopy and ion-scattering spectrometry. The results were used to assign Raman bands to fundamental vibrations of the surface tungstate and to propose a mechanism of interaction between H2O and the surface tungstate that hitherto has not been addressed for WO3—AI2O3.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jrs.1250150415
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    Paper (German National Licenses)
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