Doppelresonanzuntersuchung der Hyperfeinstruktur des 52 P 3/2-Terms im K I-Spektrum zur Bestimmung des elektrischen Kernquadrupolmoments des K40

The double-resonance method has been used to measure the hyperfinestructure of the 5² P _3/2-term in the potassium I-spectrum, using a sample enriched in theK ⁴⁰ isotope. The interaction constants ofK ⁴⁰ have been determined to beA ⁴⁰=?(2.450±0.046) MHz andB ⁴⁰=?(1.31±0.33) MHz. From these the electric quadrupolmoment has been calculated to be

$$Q(K^{40} ) = - (0 \cdot 093 \pm 0 \cdot 025) \cdot 10^{ - 24} cm^2 .$$     

Bestimmung der Kernquadrupolmomente der beiden stabilen Europiumisotope aus dem Eu II-Spektrum

The hyperfine structure of the transitions 4f ⁷ 6p ⁹ P _3,4,5?4f ⁷ 6s ⁹ S ₄,⁷ S ₃ in the spark spectrum of europium was investigated by a digital recording double-Fabry-Perot-spectrometer. Enriched samples of¹⁵¹Eu and¹⁵³Eu were used in hollow cathode light sources cooled in liquid air. As the hyperfine splitting of the⁹ P levels was not completely resolved the patterns were analysed by a computer. TheA- andB-values of the⁹ P levels were determined for both isotopes. Together with the experimentalA-values of the⁷ P levels theseA-values were used to check the eigenfunctions ofBordarier, Judd, andKlapisch, which have been calculated for intermediate coupling. Good agreement between observed and calculatedA-values was reached only if the spherical-symmetric part of the magnetic hyperfine interaction operator of the 6p-electron was used as a free parameter. In this way the configuration interaction between 4f ⁷ 6p and 4f ⁶ 6s 6d can be taken into account. Fortunately this mixing does not affect the quadrupole interaction. Therefore the quadrupole moments were derived from the measuredB-values using the unperturbed eigenfunctions. The resultsQ(¹⁵¹Eu)=(1.12 ±0.07) · 10^?24 cm² andQ(¹⁵³Eu)=(2.85 ± 0.18) · 10^?24cm² are in complete agreement with the values obtained byMüller, Steudel, andWalther in the 4f⁷ 6s 6p levels of the arc spectrum of europium. The values found for the hyperfine anomaly agree very well with the values derived from levels in Eu I and Eu III.     

Messung des Energieumsatzes in biologischen Systemen mit stabilen Isotopen

Abstract

Effects of millipedes and earthworms on the decomposition of ¹⁵N-labelled litter of winter oilseed rape were investigated in a microcosm field experiment over a period of 264 days on an oat field near Göttingen managed by integrated farming.

A total of 32 microcosms were filled with defaunated soil. ¹⁵N-labelled rape litter was placed either on top of the soil or buried into the soil simulating mulching and ploughing, respectively. To the microcosms nine adult individuals of Blaniulus guttulatus (Diplopoda) and two of Aporrectodea caliginosa (Lumbricidae) were added separately or in combination.

In general, the presence of the animals accelerated the decomposition rate of the litter material. The effects were most pronounced in the presence of Aporrectodea caliginosa. The total amount of nitrate, ammonium and the amount of ¹⁵N leached from the microcosms was increased in the presence of earthworms or of both earthworms and millipedes. Both species proved to be important members of the detritus food web of the agricultural system studied.     

Lichtelektrische Messung des inneren elektrischen Feldes in inhomogenen ...

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Lichtelektrische Messung des inneren elektrischen Feldes in inhomogenen ...

     

Lichtelelektrische Messung des inneren elektrischen Feldes in inhomogenen Halbleitern

Zusammenfassung An Germanium-Einkristallen mit inhomogener Störstellenverteilung wird die Tauc'sche Theorie des Volumphotoeffektes experimentell be-wiesen. Es wurde eine Methode, zur direkten Ausmessung des inneren elektrischen Feldes ausgearbeitet, welche es gestattet, Germaniumkristalle bezüglich ihrer Homogenität auszuwsrten.     

Die Halbwertszeit des Rb87

The half-life of Rb⁸⁷ was measured by the following method: NaJ(Tl)+RbJ- and CsJ(Tl)+RbJ-scintillation crystals were grown containing 1.13 and 13 weightpercent RbJ resp. The integral counting rates of these crystals were determined by extrapolation of the integral spectrum from 4 keV (NaJ(Tl)) and 6 keV (CsJ(Tl)) to sero energy. Then these crystals were pulverized, and the powder was counted in layers of saturation thickness in a Methan flow counter. The counting rates of the flow counter were attached to the Rb-contents of the layers by measuring mixtures of NaJ(Tl)+RbJ- and CsJ(Tl)+RbJ-powder of known compositions. By this procedure we determined the specific activity of natural Rubidium at (744±15) cps/g and the half-life of Rb⁸⁷ at (5.80±0.12) 10¹⁰ years. This result agrees with other determinations obtained with scintillation crystals, but disagrees with results obtained with counter tubes and geological determinations.     

Die Verteilungen des elektrischen und magnetischen Mikrofeldes im relativistischen Plasma

The probability distributions of the electric and magnetic microfield at a fixed space point in a relativistic, non-degenerate, homogeneous, and isotropic plasma in thermodynamic equilibrium are determined using the Markov-method and neglecting the particle interaction. They are found to be Holtsmarkians like the electricnon-relativistic microfield distribution, but the characteristic field strengths are increasing functions of temperature which are calculated.